Process for producing (co)polycarbonate and (co)polycarbonate composition

ABSTRACT

A process for producing a (co)polycarbonate or a (co)polyestercarbonate having a high molecular weight and excellent hue, heat stability and mechanical properties by reacting a dihydroxyl compound with a diester of carbonic acid and/or a diester of dicarbonic acid in the presence of a transesterification catalyst, wherein at least part of the reaction process is conducted in the presence of a specified organic phosphorus compound, or, in the presence of a specified organic phosphorus compound and a hindered phenol compound. A (co)polycarbonate or (co)polyester-carbonate composition having excellent hue, heat stability and mechanical properties, comprising a (co)polycarbonate and/or a (co)polyestercarbonate and, a specified organic phosphorus compound, or, a specified organic phosphorus compound and a hindered phenol compound.

This is a division of Ser. No. 07/940 310, filed Aug. 31, 1992, now U.S.Pat. No. 5,278,279.

FIELD OF THE INVENTION

The present invention relates to a process for producing aheat-stabilized (co)polycarbonate and a heat-stabilized(co)polycarbonate composition. In particular, the present inventionrelates to a process for producing a heat-stabilized (co)polycarbonateor a heat-stabilized (co)polyestercarbonate by the melt polycondensationof a dihydroxy compound with a diester of carbonic acid and/or a diesterof dicarbonic acid in the presence of a transesterification catalyst andan organic phosphorus compound as a heat-stabilizer.

DESCRIPTION OF THE RELATED ART

High-molecular polycarbonates are general-purpose engineeringthermoplastics usable over a wide application range, particularly forinjection molding or as the substitute for glass to be used inwindowpanes.

Although the interfacial polycondensation process is usually effectivein producing polycarbonates, it has the defects of poisonous phosgenebeing used and chlorine ions remain in the produced polycarbonate.

Japanese Patent Laid-Open No. 182836/1988 discloses the production of apolycarbonate by the interfacial polycondensation of a specifieddihydric phenol with liquid trichloromethyl chloroformate which is aphosgene dimer in place of the poisonous phosgene so as to overcomethese defects. However, only 9,9-bis(4-hydroxyphenyl)fluorenes aredescribed therein as the specified dihydric phenols.

Further, although it is described in Angew. Chem. 99,922 (1987) that apolycarbonate is produced from 2,2-bis(4-hydroxyphenyl)propane by usingtriphosgene in place of the poisonous phosgene, a reaction mechanismwherein phosgene is generated is also described therein.

Japanese Patent Laid-Open No. 51719/1985 discloses a process forproducing a polycarbonate by using a catalyst comprising a combinationof a nitrogenous basic compound and a boron compound. Although apolycarbonate having a relatively pale color can be obtained by usingthis catalyst, the catalyst has a defect of a low polymerizationactivity.

Japanese Patent Laid-Open No. 151286/1986 discloses a process forproducing a polycarbonate by using a quaternary nitrogenous compound asa catalyst, a phosphonite compound and a hinderd phenol compound.

Japanese Patent Laid-Open No. 54228/1991 discloses a process forproducing a polycarbonate in the presence of an electron-donativephosphorus compound as a catalyst.

Japanese Patent Laid-Open No. 86844/1992 discloses a polycarbonate resincomposition comprising a specified polycarbonate resin and a phosphitecompound having a fluorine atom.

Furthermore, Japanese Patent Laid-Open No. 36846/1992 discloses anaromatic polycarbonate resin composition comprising an aromaticpolycarbonate resin and at least one member selected from the groupconsisting of phosphorus compounds as an antioxidant, phenol compoundsas an antioxidant and epoxy compounds as a stabilizer.

SUMMARY OF THE INVENTION

The present inventors have found that a heat-stabilized(co)polycarbonate substantially free from chlorine ions can be obtainedwithout using the poisonous phosgene by the melt polycondensation of adiester of carbonic acid with a dihydroxy compound by using a specifiedcatalyst in the presence of a specified organic phosphorus compound as aheat-stabilizer. The present invention has been completed on the basisof this finding.

Thus, the first embodiment of the present invention provides a processfor producing a (co)polycarbonate or a (co)polyestercarbonate byreacting a dihydroxyl compound with a diester of carbonic acid and/or adiester of dicarbonic acid in the presence of a transesterificationcatalyst, wherein at least part of the reaction process is conducted inthe presence of an organic phosphorus compound selected from the groupconsisting of compounds represented by the following general formulas(1) to (6), or, in the presence of an organic phosphorus compoundselected from the group consisting of compounds represented by thefollowing general formulas (1) to (6) and a hindered phenol compound:##STR1## wherein R^(a), R^(b) and R^(c) each represents a straight-chainor branched alkyl group having 1 to 12 carbon atoms, or a phenyl groupwhich may be substituted: ##STR2## wherein R^(d), R^(e), R^(f), R^(g),R^(h), R^(i), R^(j) and R^(k) each represents a hydrogen atom or astraight-chain or branched alkyl group having 1 to 12 carbon atoms,R^(q) and R^(r) each represents a straight-chain or branched alkyl grouphaving 1 to 12 carbon atoms and R^(s) and R^(t) each represents astraight-chain or branched alkyl group having 1 to 12 carbon atoms;##STR3## wherein R^(u) and R^(v) each represents a straight-chain orbranched alkyl group having 1 to 20 carbon atoms and R^(w) represents aphenyl or aralkyl group which may be substituted.

The process described above includes a process for producing aheat-stabilized polycarbonate by melt-polycondensing a dihydric phenolwith a carbonic diester, characterized by using a catalyst selected fromamong basic nitrogen compounds and/or a catalyst selected from the groupconsisting of alkali metal compounds and alkaline earth metal compoundsin the presence of a heat-stabilized organophosphorus compound.

In the process according to the first embodiment of the presentinvention, 10⁻⁶ to 10⁻¹ mol, based on 1 mol of the dihydroxy compound,of a catalyst selected from among basic nitrogen compounds and 10⁻⁷ to10⁻² mol, based on the dihydroxy compound, of a catalyst selected fromthe group consisting of alkali metal compounds and alkaline earth metalcompounds are preferably used.

In the process according to the first embodiment of the presentinvention, 1.01 to 1.5 mol, based on 1 mol of the dihydroxy compound, ofthe diester of carbonic acid and/or the diester of dicarbonic acidis(are) preferably used to protect the terminal of the formed(co)polycarbonate and/or (co)polyestercarbonate with a carbonic estergroup.

In the process according to the first embodiment of the presentinvention, the dihydroxy compound, and the diester of carbonic acidand/or the diester of dicarbonic acid are preferably used to produce a(co)polycarbonate and/or (co)polyestercarbonate having the terminalhydroxyl content of 3 to 80 molar %.

Furthermore, in the above-described process, the dihydroxy compound ispreferably selected from among compounds of the following generalformulas (I) to (IV): ##STR4## wherein R¹, R² , R³, R⁴ and R⁵ eachrepresents a hydrogen atom, a straight-chain or branched alkyl grouphaving 1 to 8 carbon atoms or a phenyl group, X represents a halogenatom, R represents 0 to 4, and m represents 1 to 4.

The present inventors have also found that a heat-stabilized(co)polycarbonate composition can be obtained by adding a specifiedorganic phosphorus compound as a heat-stabilizer to a (co)polycarbonate.The present invention has been completed on the basis of this finding.

Thus, the second embodiment of the present invention provides a processfor producing a (co)polycarbonate composition or a(co)polyestercarbonate composition, wherein an organic phosphoruscompound selected from the group consisting of compounds represented bythe following general formulas (1) to (6), or, an organic phosphoruscompound selected from the group consisting of compounds represented bythe following general formulas (1) to (6) and a hindered phenol compoundis(are) added to a (co)polycarbonate or a (co)polyestercarbonate:##STR5## wherein R^(a), R^(b) and R^(c) each represents a straight-chainor branched alkyl group having 1 to 12 carbon atoms, or a phenyl groupwhich may be substituted; ##STR6## wherein R^(d), R^(e), R^(f), R^(g),R^(h), R^(i), R^(j) and R^(k) each represents a hydrogen atom or astraight-chain or branched alkyl group having 1 to 12 carbon atoms,R^(q) and R^(r) each represents a straight-chain or branched alkyl grouphaving 1 to 12 carbon atoms and R^(s) and R^(t) each represents astraight-chain or branched alkyl group having 1 to 12 carbon atoms;##STR7## wherein R^(u) and R^(v) each represents a straight-chain orbranched alkyl group having 1 to 20 carbon atoms and R^(w) represents aphenyl or aralkyl group which may be substituted.

The present invention further provides, as the third embodiment of thepresent invention, a (co)polycarbonate or (co)polyester-carbonatecomposition comprising or consisting essentially of a (co)polycarbonateand/or a (co)polyestercarbonate and, an organic phosphorus compoundselected from the group consisting of compounds represented by thefollowing general formulas (1) to (6), or, an organic phosphoruscompound selected from the group consisting of compounds represented bythe following general formulas (1) to (6) and a hindered phenolcompound: ##STR8## wherein R^(a), R^(b) and R^(c) each represents astraight-chain or branched alkyl group having 1 to 12 carbon atoms, or asubstituted or unsubstituted phenyl group ##STR9## wherein R^(d), R^(e),R^(f), R^(g), R^(h), R^(i), R^(j) and R^(k) each represents a hydrogenatom or a straight-chain or branched alkyl group having 1 to 12 carbonatoms, R^(q) and R^(r) each represents a straight-chain or branchedalkyl group having 1 to 12 carbon atoms and R^(s) and R^(t) eachrepresents a straight-chain or branched alkyl group having 1 to 12carbon atoms; ##STR10## wherein R^(u) and R^(v) each represents astraight-chain or branched alkyl group having 1 to 20 carbon atoms andR^(w) represents a phenyl or aralkyl group which may be substituted.

The composition described above includes a heat-stabilized polycarbonatecomposition comprising or consisting essentially of the polycarbonateproduced by the process according to the first embodiment of the presentinvention and a hindered phenol compound.

In the composition according to the present invention, the(co)polycarbonate and/or the (co)polyestercarbonate are preferably thosewhich have a terminal hydroxyl content of 3 to 80 molar % , a sodiumcontent of 1 ppm or less, an iron content of 1 ppm or less, and achlorine content of 3 ppm or less.

In the above-described present invention, the organic phosphoruscompound is preferably used in an amount of from 10 to 1,000 ppm basedon the dihydroxy compound.

DETAILED DESCRIPTION OF THE INVENTION

In the present invention, the term, "a (co)polycarbonate" means apolycarbonate and/or a copolycarbonate, and the term, "a(co)polyestercarbonate" means a polyestercarbonate and/or acopolyestercarbonate.

In the present invention, specified organic phosphorus compoundsrepresented by the following general formulas (1) to (6) are employed asa heat-stabilizer: ##STR11## wherein R^(a), R^(b) and R^(c) eachrepresents a straight-chain or branched alkyl group having 1 to 12carbon atoms, or a phenyl group which may be substituted; ##STR12##wherein R^(d), R^(e), R^(f), R^(g), R^(h), R^(i), R^(j) and R^(k) eachrepresents a hydrogen atom or a straight-chain or branched alkyl grouphaving 1 to 12 carbon atoms, R^(q) and R^(r) each represents astraight-chain or branched alkyl group having 1 to 12 carbon atoms andR^(s) and R^(t) each represents a straight-chain or branched alkyl grouphaving 1 to 12 carbon atoms; ##STR13## wherein R^(u) and R^(v) eachrepresents a straight-chain or branched alkyl group having 1 to 20carbon atoms and R^(w) represents a phenyl or aralkyl group which may besubstituted.

The phosphorus compounds represented by the general formula (1) include,for example, compounds of the following formulas: ##STR14## wherein R¹⁰represents hydrocarbon group having 1 to 30 carbon atoms; ##STR15##wherein R¹¹ represents a hydrocarbon group having 1 to 30 carbon atoms;and ##STR16##

The phosphorus compounds represented by the general formula (2) include,for example, compound of the following formula: ##STR17##

The phosphorus compound represented by the general formula (5) include,for example, compound of the following formula: ##STR18##

As the organic phosphorus compound, those except for triethyl phosphine,tri-n-propyl phoshine, triisopropyl phosphine, tri-n-butyl phoshine,triphenyl phosphine, tri-o-dimethoxyphenyl phosphine, tri-p-tolylphosphine, tri-o-tolyl phosphine, tributyl phosphite, triphenylphosphite, tri-p-tolyl phosphite and tri-o-tolyl phosphite arepreferably employed.

In general, the organic phosphorus compound is one member selected fromthe group consisting of compounds represented by the following generalformulas (1) and (7) to (11): ##STR19## wherein R^(a), R^(b) and R^(c)each represents a straight-chain or branched alkyl group having 1 to 12carbon atoms, or a phenyl group which may be substituted; ##STR20##wherein R^(d) , R^(e) , R^(f), R^(g), R^(h), R^(i), R^(j) and R^(k) eachrepresents a hydrogen atom or a straight-chain or branched alkyl grouphaving 1 to 12 carbon atoms, R^(q) and R^(r) each represents astraight-chain or branched alkyl group having 1 to 12 carbon atoms,R^(s) and R^(t) each represents a straight-chain or branched alkyl grouphaving 1 to 12 carbon atoms, R^(u) and R^(v) each represents astraight-chain or branched alkyl group having 1 to 20 carbon atoms, andPh represents a phenyl group.

Examples of the organic phosphorus compound include triethyl phosphite,triisopropyl phosphite, triisodecyl phosphite, tridodecyl phosphite,phenyl diisodecyl phosphite, diphenyl isodecyl phosphite, triphenylphosphite, phenyl bis(4-nonylphenyl) phosphite, tris(4-octyl-phenyl)phosphite, tris(4-(1-phenylethyl)phenyl) phosphite,tris(2,4-di-tert-butylphenyl) phosphite, tris(4-nonylphenyl) phosphite,diethyl 3,5-di-tert-butyl-4-hydroxybenzyl phosphonate,tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphite of thefollowing formula: ##STR21## pentaerythritoldi[(2,6-di-tert-butyl-4-methylphenyl) phosphite] of the followingformula: ##STR22## pentaerythritol di[(2,4-di-tert-butylphenyl)phosphite] of the following formula: ##STR23##tetrakis(2,4-di-tert-butylphenyl)-4,4'-(2,2-diphenylpropane) phosphiteof the following formula: ##STR24##

dialkoxyphenylphosphoric acids of the following formula: ##STR25##wherein R^(u) and R^(v) each represent a straight-chain or branchedalkyl group having 1 to 20 carbon atoms and Ph represents a phenylgroup,

and the phosphonite compound, which is commercially available from Sandunder the trade name of "Sandstab P-EPQ", of the following formula:##STR26##

Typical examples of the organic phosphorus compounds usable in thepresent invention include triethyl phosphite, triisopropyl phosphite,triisodecyl phosphite, tridodecyl phosphite, phenyl diisodecylphosphite, diphenyl isodecyl phosphite, triphenyl phosphite, phenylbis(4-nonylphenyl) phosphite, tris(4-octylphenyl) phosphite,tris(4-(1-phenylethyl)phenyl) phosphite, tris(2,4-di-tert-butylphenyl)phosphite, diethyl 3,5-di-tert-butyl-4-hydroxybenzyl phosphonate,tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphite of thefollowing formula: ##STR27## pentaerythritoldi[(2,6-di-tert-butyl-4-methylphenyl) phosphite] of the followingformula: ##STR28## pentaerythritol di[(2,4-di-tert-butylphenyl)phosphite] of the following formula: ##STR29##tetrakis(2,4-di-tert-butylphenyl) 4,4'-(2,2diphenylpropane) phosphite ofthe following formula: ##STR30## and dialkoxyphenylphosphoric acids ofthe following formula: ##STR31## wherein R^(u) and R^(v) each representa straight-chain or branched alkyl group having 1 to 20 carbon atoms andPh represents a phenyl group.

In the present invention, the organic phosphorus compound is preferablyone member selected from the group consisting of triisopropyl phosphite,triisodecyl phosphite, tridodecyl phosphide, phenyl diisodecylphosphite, diphenyl isodecyl phosphite, phenyl bis(4-nonylphenyl)phosphite, tris(4-octyl-phenyl) phosphite, tris(4-(1-phenylethyl)phenyl)phosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylenediphosphite of the following formula: ##STR32## pentaerythritoldi[(2,4-di-tert-butylphenyl) phosphite] of the following formula:##STR33## tetrakis(2,4-di-tert-butylphenyl)-4,4'-(2,2-diphenylpropane)phosphite of the following formula: ##STR34## anddialkoxyphenylphosphoric acids of the following formula: ##STR35##wherein R^(u) and R^(v) each represent a straight-chain or branchedalkyl group having 1 to 20 carbon atoms and Ph represents a phenylgroup,

and still preferably one member selected from the group consisting oftetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphite of thefollowing formula: ##STR36##tetrakis(2,4-di-tert-butylphenyl)-4,4'-(2,2-diphenylpropane) phosphiteof the following formula: ##STR37## and dialkoxyphenylphosphoric acidsof the following formula: ##STR38## wherein R^(u) and R^(v) eachrepresent a straight-chain or branched alkyl group having 1 to 20 carbonatoms and Ph represents a phenyl group.

The above-described phosphorus compounds can be used either singly or incombination of two or more of them.

The hindered phenol compounds usable in the present invention includeN,N'-hexamethylene-bis(3,5-di-t-butyl-4-hydroxyhydrocinnamamide),triethylene glycol bis[3-(3-t-butyl-5-methyl-4hydroxyphenyl)propionate],1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxy-phenyl)propionate],pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxy-phenyl)propionate],3,5-di-t-butyl-4-hydroxybenzyl phosphonate-diethyl ester,1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene andcompounds of the following formulas: ##STR39## wherein R^(x) representsa straight-chain or branched alkyl group having 1 to 24 carbon atoms.

The hindered phenol compound is preferably one member selected from thegroup consisting of octadecylpropionate-3-(3,5-di-t-butyl-4-hydroxyphenyl); i.e., octadecyl3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,N,N'-hexamethylene-bis(3,5-di-t-butyl-4-hydroxyhydrocinnamamide),triethylene glycolbis-[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate],1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxy-phenyl)propionate],3,5-di-t-butyl-4-hydroxybenzyl phosphonate-diethyl ester,1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxy-benzyl)benzeneand compounds of the following formulas: ##STR40## and still preferablyone member selected from the group consisting ofN,N'-hexamethylene-bis(3,5-di-t-butyl-4-hydroxyhydrocinnamamide),triethylene glycolbis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate],1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],3,5-di-t-butyl-4-hydroxybenzyl phosphonate-diethyl ester,1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene andcompounds of the following formulas: ##STR41##

Various commercially available hindered phenol compounds are usable inthe present invention and examples thereof includetetrakis[methylene-3-(3,5'-di-t-butyl-4-hydroxyphenyl)propionate]methane (a product ofCiba-Geigy, Irganox®1010) and1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene (aproduct of Shell, Ionox®330).

The above-described hindered phenol compounds can be used either singlyor in combination of two or more of them.

Representative examples of the transesterification catalyst usable inthe present invention include

(a) metal-containing catalysts such as lithium borohydride, sodiumborohydride, potassium borohydride, rubidium borohydride, cesiumborohydride, beryllium borohydride, magnesium borohydride, calciumborohydride, strontium borohydride, barium borohydride, aluminumborohydride, titanium borohydride, tin borohydride, germaniumborohydride, tetraphenoxylithium, tetraphenoxysodium,tetraphenoxypotassium, tetraphenoxyrubidium, tetraphenoxycesium, sodiumthiosulfate, beryllium oxide, magnesium oxide, tin(IV) oxide, dibutyltinoxide, beryllium hydroxide, magnesium hydroxide, germanium hydroxide,beryllium acetate, magnesium acetate, tin(IV) acetate, germaniumacetate, lithium carbonate, sodium carbonate, potassium carbonate,beryllium carbonate, magnesium carbonate, tin(IV) carbonate, germaniumcarbonate, tin(IV) nitrate, germanium nitrate, antimony trioxide andbismuth trimethylcarboxylate;

(b) electron-donative amines such as N,N-dimethyl-4-aminopyridine,4-diethylaminopyridine, 4-aminopyridine, 2-aminopyridine,2-hydroxypyridine, 2-methoxypyridine, 4-methoxypyridine,4-hydroxypyridine, 2-dimethylaminoimidazole, 2-methoxyimidazole,2-mercaptoimidazole, aminoquinoline, imidazole, 2-methylimidazole,4-methylimidazole and diazabicyclooctane (DABCO);

(c) salts of the above electron-donative amines with carbonic, acetic,formic, nitric, nitrous, oxalic, borofluoric and hydrofluoric acids;

(d) electron-donative phosphorus compounds such as triethylphosphine,tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine,triphenylphosphine, tri-o-dimethoxyphenylphosphine,tri-p-tolylphosphine, tri-o-tolylphosphine, tributyl phosphite,triphenyl phosphite, tri-p-tolyl phosphite and tri-o-tolyl phosphite;and

(e) borane complexes such as complexes of borane with ammonia,dimethylamine, trimethylamine, triethylamine, t-butylamine,dimethylaniline, pyridine, dimethylaminopyridine, morpholine,piperazine, pyrrole, tetrahydrofuran, dimethyl sulfide,tri-n-butylphosphine, triphenylphosphine or triphenyl phosphite.

In the present invention, the transesterification catalyst is preferablya basic compound containing a nitrogen atom in the molecule, or, a basiccompound containing a nitrogen atom in the molecule and an alkalinemetal compound and/or an alkaline earth metal compound.

The basic compound containing a nitrogen atom in the molecule ispreferably one member selected from the group consisting of basiccompounds containing a nitrogen atom in the molecule except for salts ofquaternary nitrogen-containing compounds, or, one member selected fromthe group consisting of basic compounds containing a nitrogen atom inthe molecule except for quaternary ammonium halides, quaternarypyridinium halides, quaternary picolinium halides, quaternaryquinolinium halides and quaternary isoquinolinium halides.

Examples of the basic compound containing a nitrogen atom in themolecule include aliphatic primary amines, aliphatic secondary amines,aliphatic tertiary amines, alicyclic primary amines, alicyclic secondaryamines, alicyclic tertiary amines, aromatic primary amines, aromaticsecondary amines, aromatic tertiary amines, quaternary ammonium saltsand ammonia.

Concretely, the basic compound containing a nitrogen atom in themolecule include ammonia, ammonium hydroxides, ammonium borohydrides,ammonium tetraarylborates, pyridines, imidazoles, diazo compounds,picolines, pyrimidines, quinolines, pyrazoles, aniline, pyrrolidines,morpholines, piperidines and piperadines.

Typical examples of the basic compound containing a nitrogen atom in themolecule usable in the present invention include ammonium hydroxideshaving an alkyl, aryl or aralkyl group, such as tetramethylammoniumhydroxide (Me₄ NOH), tetraethylammonium hydroxide (Et₄ NOH),tetrabutylammonium hydroxide (Bu₄ NOH) and trimethylbenzylammoniumhydroxide (C₆ H₅ --CH₂ (Me)₃ NOH); tertiary amines such astrimethylamine, triethylamine, dimethylbenzylamine and triphenylamine;secondary amines represented by the formula: R₂ NH wherein R representsan alkyl group such as a methyl or ethyl group or an aryl group such asa phenyl or toluyl group; primary amines represented by the formula:RNH₂ wherein R is as defined above; ammonia; and basic salts such astetramethylammonium borohydride (Me₄ NBH₄), tetrabutylammoniumborohydride (Bu₄ NBH₄), tetramethylammonium tetraphenylborate (Bu4NBPh4)and tetrabutylammonium tetraphenylborate (Me₄ NBPh₄).

In addition, the following compounds can also be used:4-(4-methyl-1-piperidinyl)pyridine, N,N-dimethyl-4-aminopyridine,4-diethylaminopyridine, 4-pyrrolidinopyridine, 4-aminopyridine,2-aminopyridine, 2-hydroxypyridine, 2-methoxypyridine,4-methoxypyridine, 4-hydroxypyridine, 2-dimethylaminoimidazole,2-methoxyimidazole, 2-mercaptoimidazole, aminoquinoline, benzimidazole,imidazole. 2-methylimidazole, 4-methylimidazole, diazabicyclooctane(DABCO), 1,8-diaza-bicyclo[5,4,0]-7-undecene (DBU) and4-(4-methylpyrrolidinyl)pyridine.

The basic compound containing a in nitrogen atom in the molecule ispreferably one member selected from the group consisting of pyridines,imidazoles, diazo compounds, picolines, pyrimidines, quinolines,pyrazoles, aniline, pyrrolidines, morpholines, piperidines andpiperadines, and still preferably 4-dimethylaminopyridine or4-pyrrolidinopyridine.

Typical examples of the alkali metal compounds usable in the presentinvention include sodium hydroxide, potassium hydroxide, lithiumhydroxide, sodium hydrogencarbonate, potassium hydrogencarbonate,lithium hydrogencarbonate, sodium carbonate, potassium carbonate,lithium carbonate, sodium acetate, potassium acetate, lithium acetate,sodium stearate, potassium stearate, lithium stearate, sodiumborohydride, lithium borohydride, potassium borohydride, sodiumtetraphenylborate, sodium benzoate, potassium benzoate, lithiumbenzoate, disodium hydrogenphosphate, dipotassium hydrogenphosphate,dilithium hydrogenphosphate, disodium, dipotassium or dilithium salt ofbisphenol A, or sodium, potassium or lithium salt of phenol.

Typical examples of the alkaline earth metal compounds usable in thepresent invention include calcium hydroxide, barium hydroxide, magnesiumhydroxide, strontium hydroxide, calcium hydrogencarbonate, bariumhydrogencarbonate, magnesium hydrogencarbonate, strontiumhydrogencarbonate, calcium carbonate, barium carbonate, magnesiumcarbonate, strontium carbonate, calcium carbonate, barium acetate,magnesium acetate, strontium acetate, calcium stearate, barium stearate,magnesium stearate and strontium stearate.

Typical examples of the diester of carbonic acid, i.e., carbonicdiester, usable in the present invention include bisaryl carbonates suchas diphenyl carbonate, bis(2,4-dichlorophenyl) carbonate,bis-(2,4,6-trichlorophenyl) carbonate, bis(2-cyanophenyl) carbonate,bis(o-nitrophenyl) carbonate, ditolyl carbonate, m-cresyl carbonate,dinaphthyl carbonate, bis(biphenyl) carbonate and the like: dicycloalkylcarbonates such as dicyclohexyl carbonate and the like; and dialkylcarbonates such as dimethyl carbonate, diethyl carbonate, dibutylcarbonate and the like. Among these, bisaryl carbonates are preferable,and diphenyl carbonate is particularly preferred.

In the present invention, a mixture of the above-described carbonicdiester(s) and a diester of dicarbonic acid, i.e., dicarboxylic ester(s)can be used. The mixture may contain 50 molar % or less of dicarboxylicesters. A (co)polyestercarbonate is obtained in such a case. Examples ofthe dicarboxylic ester include diphenyl terephthalate or diphenylisophthalate.

Typical examples of the dihydroxy compound, i.e., dihydric phenol,usable in the present invention include compounds of the followinggeneral formulas (I) to (IV): ##STR42## wherein R¹, R², R³,R⁴ and R⁵each represents a hydrogen atom, a straight-chain or branched alkylgroup having 1 to 8 carbon atoms or a phenyl group, X represents ahalogen atom, n represents 0 to 4, and m represents 1 to 4.

Furthermore, typical examples of the dihydroxy compound, i.e., dihydricphenol, usable in the present invention include compounds of thefollowing general formulas (V) to (VII): ##STR43## wherein R₁, R₂,R₃,R₄, R₅ and R₆, which may be the same or different, each represent ahydrogen atom, an alkyl group, a cycloalkyl group, an aralkyl group oran aryl group; X_(l), X₂, Y₁, Y₂, Y₃, Z₁ and Z₂, which may be the sameor different, each represent a halogen atom, an alkoxy group, an alkylgroup, a cycloalkyl group, an aralkyl group or an aryl group; 1, m, n,p, q, r and s each represent an integer of 0-4; and t represents aninteger of 2-10.

Examples of the alkyl group include straight-chain or branched alkylgroups such as methyl group, ethyl group, n-propyl group, isopropylgroup, n-butyl group, isobutyl group, t-butyl group, n-pentyl group,isopentyl group, neopentyl group, hexyl group, heptyl group, octylgroup, 2-ethylhexyl group, decyl group, undecyl group, dodecyl group andthe like, among which preferable alkyl groups are straight-chain orbranched alkyl groups having about 1 to 8 carbon atoms.

Examples of the cycloalkyl group include cyclopropyl group, cyclopentylgroup, cyclohexyl group, cycloheptyl group, cyclooctyl group and thelike.

Examples of the aralkyl group include benzyl group, phenethyl group,benzhydryl group and the like. Examples of the aryl group include phenylgroup, naphthyl group, anthryl group and the like, among which apreferable aryl group is phenyl group.

The halogen atom includes fluorine atom, chlorine atom, bromine atom andiodine atom. The alkoxy group includes methoxy group, ethoxy group,n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group,pentyloxy group, hexyloxy group and the like.

The alkyl group, the cycloalkyl group, the aryl group and the aralkylgroup may have one or more substituents inert under the conditions ofthe transesterification reaction. Examples of such substituent Include ahalogen atom, an alkoxy group, an aryloxy group, an aralkyloxy group, analkylthio group, a cyano group, a nitro group and the like.

The dihydric phenols which are the compounds represented by the abovegeneral formula (I) include, for example,2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane.2.2-bis(4-hydroxyphenyl)-4-methylpentane,2,2-bis(4-hydroxyphenyl)octane, 4,4'-dihydroxy-2,2,2-triphenylethane and2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane.

The dihydric phenols which are the compounds represented by the abovegeneral formula (II) include, for example,2,2-bis(4-hydroxy-3-methylphenyl)propane,2,2-bis(4-hydroxy-3-isopropylphenyl)propane,2,2bis(4-hydroxy-3-sec-butylphenyl)propane,2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane and2,2-bis(4-hydroxy-3-tert-butylphenyl)propane.

The dihydric phenols which are the compounds represented by the abovegeneral formula (III) include, for example,1,1'-bis(4-hydroxyphenyl)-p-diisopropylbenzene and1,1'-bis(4-hydroxyphenyl)-m-diisopropylbenzene.

The dihydric phenols which are the compounds represented by the abovegeneral formula (IV) include. for example,1,1'-bis(4-hydroxyphenyl)cyclohexane.

It is also possible to produce a copolycarbonate or acopolyestercarbonate by the use of a mixture comprising two or moredihydric phenols.

The process according to the first embodiment of the present inventionis conducted by reacting a dihydroxyl compound with a diester ofcarbonic acid and/or a diester of dicarbonic acid in the presence of atransesterification catalyst, and in the presence of an organicphosphorus compound selected from the group consisting of compoundsrepresented by the afore-mentioned general formulas (1) to (6) or in thepresence of an organic phosphorus compound selected from the groupconsisting of compounds represented by the afore-mentioned generalformulas (1) to (6) and a hindered phenol compound for at least part ofthe reaction process.

That is, the process includes those which are conducted bymelt-polycondensing a dihydric phenol such as bisphenol A with acarbonic diester such as diphenyl carbonate by using a catalyst selectedfrom among basic nitrogen compounds and/or a catalyst selected from thegroup consisting of alkali metal compounds and alkaline earth metalcompounds in the presence of an organophosphorus compound as aheat-stabilizer.

The reaction proceeds at a temperature in the range of 100° to ca.300°C., preferably 130° to 280° C. When the reaction temperature is below100° C., the reaction velocity is insufficient and when it exceeds 300°C., side reactions are apt to occur.

Thus, it is necessary to use an organic phosphorus compound contributiveto the heat stabilization in an amount of 10 ppm or more based on thedihydroxy compound. When this amount is less than 10 ppm, no heatstabilizing effect can be obtained. In general, an organic phosphoruscompound is added in an amount of 10 to 1000 ppm based on the dihydroxycompound. When it exceeds 1000 ppm, adverse effects are exerted on theproperties unfavorably as the case may be.

The amount of the hindered phenol compound to be added is preferably 10to 2,000 ppm based on the dihydroxy compound. When it is less than 10ppm, no heat stabilizing effect can be obtained and, on the contrary,when it exceeds 2,000 ppm, adverse effects are exerted on the propertiesunfavorably as the case may be.

In the case that the organic phosphorus compound represented by thegeneral formula (7) is employed, the amount thereof is preferably in anamount of 0.1 to 0.5% by weight based on the whole polycondensate. Inthe case that the organic phosphorus compound represented by the generalformula (7) and a hindered phenol compound are used, the total amount ofthe phosphorus compound and the hindered phenol compound must be 0.5% orbelow based on the whole polycondensate. The addition thereof in anamount exceeding 0.5% by weight will exert an adverse effect on themechanical properties of tile polycarbonate unfavorably as the case maybe.

When a basic compound containing a nitrogen atom is employed as thetransesterification catalyst, the amount thereof is preferably 10⁻⁶ go10⁻¹ mol, still preferably 10⁻⁴ to 10⁻², based on the dihydroxy compoundcontained in the reaction system. When it is less than 10⁻⁶ mol, thecatalytic effect is insufficient and the polymerization velocity of the(co)polycarbonate or the (co)polyestercarbonate is reduced and, on thecontrary, when it exceeds 10⁻¹ mol, the relative amount thereofremaining as the catalyst in the resulting (co)polycarbonate or the(co)polyestercarbonate is increased to impair the properties of the(co)polycarbonate or the (co)polyestercarbonate.

When an alkali metal compound and/or an alkaline earth metal compoundis(are) employed as the transesterification catalyst, the amount thereofis preferably 10⁻⁷ to 10⁻² mol, still preferably 10⁻⁶ to 10⁻³ mol, basedon the dihydroxy compound contained in the reaction system. When it isless than 10⁻⁷ mol, the catalytic effect is insufficient and the degreeof polymerization of the (co)polycarbonate or the (co)polyestercarbonateis reduced and, on the contrary, when it exceeds 10⁻² mol, the relativeamount thereof remaining as the catalyst in the resulting(co)polycarbonate or (co)polyestercarbonate is increased to impair theproperties of them.

The terminal hydroxyl content of the (co)polycarbonate or the(co)polyestercarbonate obtained in the present invention is preferablyin the range of 3 to 80 molar %. That is, it is preferable that thedihydroxyl compound and, the diester of carbonic acid and/or the diesterof dicarbonic acid are used to produce a (co)polycarbonate or(co)polyestercarbonate having its terminal hydroxyl content of 3 to 80molar %. It is practically difficult to realize a terminal hydroxylcontent of less than 3 molar % and, on the contrary, when it exceeds 80molar %, the heat stability thereof is impaired. A (co)polycarbonate or(co)polyester-carbonate having a terminal hydroxyl content in the rangeof 3 to 50 molar % can be used singly. A (co)polycarbonate or(co)polyestercarbonate having a terminal hydroxyl content of 50 to 80molar % can be used in the form of a blend with another polymer.

The diester of carbonic acid or the diester of dicarbonic acid must beused in an amount equimolar to the dihydroxy compound contained in thereaction system. To form a high-molecular-weight (co)polycarbonate,usually 1 mol of the diester of carbonic acid must be reacted with 1 molof the dihydroxy compound. When diphenyl carbonate is used as thediester of carbonic acid, 2 mol of phenol is formed by the reaction anddistilled off from the reaction system. However, in order to prevent anadverse effect on the properties, particularly hue, of the(co)polycarbonate, it is preferred to use 1.01 to 1.5 mol, particularly1.015 to 1.20 mol, of the diester of carbonic acid per mole of thedihydroxy compound to protect the terminal hydroxyl group of theresulting (co)polycarbonate with a carbonic ester group.

The (co)polycarbonate obtained by the process according to the firstembodiment of the present invention preferably has a sodium content of 1ppm or less, an iron content of 1 ppm or less and a chlorine content of3 ppm or less. When the sodium, iron and chlorine contents exceed 1 ppm,1 ppm and 3 ppm, respectively, an adverse effect is exerted on theproperties, particularly hue, of the polycarbonate unfavorably.

In the above-described process, the addition of the organic phosphoruscompound and the hindered phenol compound is conducted, for example, asfollows:

(1) the organic phosphorus compound and the hindered phenol compound areadded in any one step before the relative viscosity of the reactionmixture reaches in the range of from 1.01 to 1.15 (polymer content: 0.5g/dl in methylene chloride, at 20° C.).

(2) the organic phosphorus compound and the hindered phenol compound areadded in any one step after the relative viscosity of the reactionmixture reaches in the range of from 1.01 to 1.15 (polymer content: 0.5g/dl in methylene chloride, at 20° C.).

(3) the organic phosphorus compound is added in any one step before therelative viscosity of the reaction mixture reaches in the range of from1.01 to 1.15 (polymer content: 0.5 g/dl in methylene chloride, at 20°C.), and the hindered phenol compound are added in anyone step after therelative viscosity of the reaction mixture reaches in the range of from1.01 to 1.15 (polymer content: 0.5 g/dl in methylene chloride, at 20°C.).

(4) the hindered phenol compound is added in any one step before therelative viscosity of the reaction mixture reaches in the range of from1.01 to 1.15 (polymer content: 0.5 g/dl in methylene chloride, at 20°C.), and the organic phosphorus compound is added in any one step afterthe relative viscosity of the reaction mixture reaches 1.01 (polymercontent: 0.5 g/dl in methylene chloride, at 20° C.).

Any one step before the relative viscosity of the reaction mixturereaches in the range of from 1.01 to 1.15 (polymer content: 0.5 g/dl inmethylene chloride, at 20° C.) includes, for example, the step beforethe reaction, and the step of pre-polycondensation. That is, theaddition of the organic phosphorus compound and/or the hindered phenolcompound is conducted together with the addition of starting monomers,i.e. dihydric phenol and carbonic diester, and the transesterificationcatalyst; or before the relative melt viscosity of the reaction mixturereaches 1.01 to 1.15, preferably about 1.1 (determined in terms ofmethylene chloride concentration at a polymer concentration of 0.5 g/dlat 20° C.) after the initiation of the reaction.

Any one step after the relative viscosity of the reaction mixturereaches in the range of from 1.01 to 1.15 (polymer content: 0.5 g/dl inmethylene chloride, at 20° C.) includes, for example, the step ofpost-polycondensation. The step of post-polycondensation begins when therelative viscosity of the reaction mixture reaches 1.01 to 1.15,generally about 1.1 (determined in terms of methylene chlorideconcentration at a polymer concentration of 0.5 g/dl at 20° C.). In thestep of post-polycondensation, the molecular weight of the polymerincreases and then the reaction completes.

The hindered phenol compound may be added together with the organicphosphorus compound or at any other time.

The process according to the second embodiment of the present inventionis conducted by adding a specified organic phosphorus compound describedabove, or, a specified organic phosphorus compound and a hindered phenolcompound to a (co)polycarbonate or a (co)polyestercarbonate to prepare a(co)polycarbonate composition or a (co)polyestercarbonate composition.That is, compounding of the specified organic phosphorus compound (and ahindered phenol compound) may be conducted during kneading, extruding orpelleting of the polymer after the completion of the reaction.

The (co)polycarbonate or the (co)polyestercarbonate is preferably thosewhich are produced by the process according to the first embodiment ofthe present Invention. However, a polycarbonate which is prepared by thephosgen method may be employed.

The amount of the organic phosphorus compound to be added is preferably1,000 to 10,000 ppm based on the dihydroxy compound. When it is lessthan 1,000 ppm, no heat stabilizing effect can be obtained and, on thecontrary, when it exceeds 10,000 ppm, adverse effects are exerted on theproperties unfavorably as the case may be.

The amount of the hindered phenol compound to be added is preferably1,000 to 50,000 ppm based on the dihydroxy compound. When it is lessthan 1,000 ppm, no heat stabilizing effect can be obtained and, on thecontrary, when it exceeds 50,000 ppm, adverse effects are exerted on theproperties unfavorably as the case may be.

The third embodiment of the present invention is a (co)polycarbonate or(co)polyestercarbonate composition comprising a (co)polycarbonate and/ora (co)polyestercarbonate and, an organic phosphorus compound selectedfrom the group consisting of compounds represented by the above generalformulas (1) to (6), or an organic phosphorus compound selected from thegroup consisting of compounds represented by the above general formulas(1) to (6) and a hindered phenol compound.

That is, the composition includes, for example, the composition obtainedby the process according to the second embodiment of the presentinvention, and the (co)polycarbonate or (co)polyestercarbonate obtainedby the process according to the first embodiment of the presentinvention if the specified organic phosphorus compound or the specifiedorganic phosphorus compound and a hindered phenol compound is(are)present as it is in the obtained polymer.

When the (co)polycarbonate used has terminal hydroxyl group content of 3to less than 50 molar %, the composition may not contain anotherpolymer. However, when the (co)polycarbonate has terminal hydroxyl groupcontent of 50 to 80 molar %, the composition may contain a polymer otherthan (co)polycarbonates and (co)polyestercarbonates, too.

According to the first embodiment of the present invention wherein atransesterification catalyst, preferably a catalyst selected from amongbasic nitrogen compounds and/or a catalyst selected from the groupconsisting of alkali metal compounds and alkaline earth metal compoundsare(is) used in the presence of an organic phosphorus compound as aheat-stabilizer, a colorless, transparent (co)polycarbonate or(co)polyestercarbonate having a high molecular weight and beingresistant to deterioration caused by heat can be obtained without usingpoisonous phosgene.

According to the second and third embodiment of the present invention, amold comprising (co)polycarbonate or (co)polyestercarbonate and beingresistant to deterioration caused by heat during processing can beobtained.

The (co)polycarbonate, (co)polyestercarbonate, (co)polycarbonatecomposition and (co)polyestercarbonatecomposition according to thepresent invention are generally used as an engineering plastic and areparticularly useful as the material of articles for outdoor use, such asoutdoor lighting fixtures, windowpanes and fences; and articles to beexposed to high temperature and high humidity, e.g., microwave ovens,tablewares, tank and pipe.

Further, they can be also applied to a heat-sensitive element of anelectric blanket or carpet, various hoses and tubes, hot-melt adhesive,and so on.

EXAMPLE EXAMPLEiA-1

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 0.164 g (2×10⁻²mol) of 2-methylimidazole and 21.4 g (0.1 mol) of diphenyl carbonatewere fed into a reactor. The contents were stirred at 180° C. in anitrogen atmosphere for one hour. The temperature of the contents wasgradually raised to 250° C., while the pressure of the system waslowered to 2 mmHg. At this point of time, 0.05 g (0.24% by weight basedon the whole polycondensate) oftetrakis(2,4-di-t-butyl-phenyl)-4,4'-biphenylenephosphonite (a productof Sand, Sandstab P-EPQ) and 0.025 g (0.1% by weight based on the wholepolycondensate) of pentaerythritoltetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (a product ofCiba-Geigy, Irganox 1010) were added to the reactor. At the point oftime of this addition the relative solution viscosity (polymerconcentration: 0.5 g/100 ml, 20° C., solvent: methylene chloride)presumed from the stirring torque was 1.17, while the one actuallydetermined by the use of a sample of the polycondensate was 1.18. Thetemperature of the contents was further raised and the contents werereacted at 280° C. in a vacuum of 0.5 mmHg for 2 hours to give apolycarbonate. This polycarbonate was nearly colorless and transparentand had an intrinsic viscosity [η] of 0.519 as determined in methylenechloride at 20° C. The average molecular weight Mv of the polycarbonatewas 29,900 as calculated according to the formula: [η]=1.11×10⁻⁴(Mv)⁰.82 (see Encyclopedia of Polymer Science and Technology, vol.10,p.732, John Wiley Sons, Inc. (1969)).

The polycarbonate prepared above was evaluated for the heat resistanceby determining the thermal decomposition behavior thereof in a nitrogenstream at a temperature rise rate of 10° C./min by the use of adifferential thermogravimetric analyzer (mfd. by Rigaku Denki K.K.). Thedecomposition-initiating temperature, T_(d) was 432° C.; thetemperature, T₅ at which the weight loss reached 5% was 470° C. and thetemperature, T₁₀ at which the weight loss reached 10% was 486° C.

Further, the polycarbonate was also evaluated for the resistance tohydrolysis by hot-pressing the polycarbonate into a sheet (50 mm×5Omm×0.6 mm), hanging down the sheet in a thermohygrostat at 90° C. and100% RH and determining a lowering in the molecular weight due tohydrolysis. After the lapse of 30 days under the conditions of 90° C.and 100% RH (relative humidity), the retention of the molecular weightwas 88.7% based on the initial molecular weight and the resulting sheetwas colorless and transparent and no abnormal phenomenon was observed inrespect of the external appearance. These results are given in Table 1.

Example A-2

Another polycarbonate was prepared in a similar manner to that ofExample A-1 except that 0.0122 g (1×10⁻⁴ mol) of 4-dimethylaminopyridinewas added instead of 2-methylimidazole, that the contents were stirredin a nitrogen atmosphere for 2 hours prior the polycondensation and that0.025 g of Sandstab P-EPQ (a product of Sand) and 0.025 g of diethyl3,5-di-t-butyl-4-hydroxybenzylphosphonate (a product Ciba-Geigy, Irganox1222) were added when the relative solution viscosity of thepolycondensate reached 1.20. The hue, average molecular weight, thermaldecomposition behavior and hydrolysis behavior of this polycarbonate aregiven in Table 1.

EXAMPLE A-3

11.4 g (50 mole %, 0.05 mole) of 2,2-bis-(4-hydroxyphenyl)propane, 17.0g (50 mole %, 0.05 mole) of 2,2-bis(4-hydroxy-3-t-butylphenyl)propane,23.0 g (0.108 mole) of diphenyl carbonate and 0.068 g (10⁻³ mol) ofimidazole were stirred together in a nitrogen atmosphere for 2 hours andsubjected to polycondensation in a similar manner to that of ExampleA-1. When the relative solution viscosity reached 1.21, 0.025 g ofSandstab P-EPQ (a produce of Sand) and 0.025 g of diethyl3,5-di-t-butyl-4-hydroxybenzylphosphonate (a product of Ciba-Geigy,Irganox 1222) were added to the reaction mixture like in Example A-2.The obtained mixture was further reacted. The hue, viscosity-averagemolecular weight, thermal decomposition behavior and hydrolysis behaviorof the obtained copolymer are given in Table 1.

EXAMPLE A-4

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 42.1 g (0.1 mol) ofbis(2,4,6-trichlorophenyl)carbonate and 0.0122 g (10⁻⁴ mol) ofdimethylaminopyridine were stirred together at 180° C. in a nitrogenatmosphere for one hour. The temperature of the mixture was raised,while gradually lowering the pressure of the system. When the relativesolution viscosity reached 1.19, 0.025 g of Sandstab P-EPQ (a product ofSand) and 0.025 g of diethyl 3,5-di-t-butyl-4-hydroxybenzylphosphonate(a product of Ciba-Geigy, Irganox 1222) were added to the reactionmixture, and the obtained mixture was further reacted like in ExampleA-2 to give a polycarbonate.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior thereof are given in Table 1.

Example A-5

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 23.0 g (0.108 mol)of diphenyl carbonate and 0.0352 g (2×10⁻⁴ mol) of4-(4-methylpyrrolidinyl)pyridine were stirred together at 180° C. in anitrogen atmosphere for one hour. The temperature of the mixture wasraised, while gradually lowering the pressure of the system. When therelative solution viscosity reached 1.02, 0.025 g of Sandstab P-EPQ (aproduct of Sand) and 0.025 g of diethyl3,5-di-t-butyl-4-hydroxybenzylphosphonate (a product of Ciba-Geigy,Irganox 1222) were added to the reaction mixture, and the obtainedmixture was further reacted like in Example A-2 to give a polycarbonate.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior thereof are given in Table 1.

Comparative Example A-1

Another polycarbonate was prepared in the same manner as that of ExampleA-1 except that a known catalyst, i.e., lithium hydroxide as an alkalimetal hydroxide was used instead of 2-methylimidazole in an amount of10⁻⁸ mole % based on the bisphenol A and that neither Sandstab P-EPQ (aproduct of Sand) nor other stabilizer was added.

Although the obtained polymer had an average molecular weight as high as26,500, the polymer was pale yellow; the thermal decomposition thereofbegan at 375° C. and the weight loss to reach 430° C. was 10%. Further,in the hydrolysis test at 90° C. and 100% RH, the retention of theaverage molecular weight after 30 days was as low as 65.3% and theresulting test sheet was translucent, had many small white spots(partially including voids) all over and was brittle remarkably. Theseresults are given in Table 1.

Comparative Example A-2

Another polycarbonate was prepared in the same manner as that ofComparative Example A-1 except that lithium carbonate as an alkali metalcarbonate was used instead of lithium hydroxide in an amount of 10hu -3mole % based on the bisphenol A and that 0.05 g of Sandstab P-EPQ (aproduct of Sand) and 0.025 g of Irganox 1010 (a product of Ciba-Geigy)were added when the relative solution viscosity of the polycondensatereached 0.8.

The obtained polymer was pale-yellow, and the thermal decompositionbehavior thereof was somewhat improved but was inferior to those of thepolymers prepared in Examples as shown in Table 1. Further, theresistance of the polymer to hydrolysis was not improved at all inrespect of the retention of molecular weight or appearance as comparedwith that of Comparative Example A-1.The hue, viscosity-averagemolecular weight, thermal decomposition behavior and hydrolysis behaviorthereof are given in Table 1.

Comparative Example A-3

Another polycarbonate was prepared in the same manner as that ofComparative Example A-1 except that tetrabutylammonium bromide was usedas the catalyst and that only 0.05 g of Irganox 1010 (a product ofCiba-Geigy) was added as a stabilizer when the relative solutionviscosity of the polycondensate reached 0.9.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior thereof are given in Table 1.

As shown in Table 1, the polycarbonate was not improved in the retentionof molecular weight and thermal decomposition behavior, though it wasimproved in the appearance after the hydrolysis test.

                                      TABLE I                                     __________________________________________________________________________                  Ex. A-1    Ex. A-2       Ex. A-3     Ex. A-4                    __________________________________________________________________________    Dihydroxy compound                                                                          bisphenol A                                                                              bisphenol A   bisphenol A 11.4                                                                          bisphenol A                              22.8 g (0.1 mol %)                                                                       22.8 g (0.1 mol %)                                                                          (0.05 mol)/2,2-bis-(4-                                                                    22.8 g (0.1 mol %)                                                hydroxy-3-t-butyl)-                                                           propane 17.0 g (0.05                                                          mol)                                   Bisaryl carbonate                                                                           diphenyl carbonate                                                                       diphenyl carbonate                                                                          diphenyl carbonate                                                                        bis(2,4,6-trichloro-                     23.0 g (0.108 mol %)                                                                     23.0 g (0.108 mol %)                                                                        23.0 g (0.108 mol                                                                         phenyl)carbonate                                                              45.5 g (0.108 mol)         Catalyst      2-methylimidazole                                                                        4-dimethylaminopyridine                                                                     imidazole   dimethylaminopyridine                    2 × 10.sup.-2                                                                      1 × 10.sup.-4                                                                         1 × 10.sup.-3                                                                       1 × 10.sup.-4        Tetrakis(2,4-di-t-                                                                          0.05 g     0.025 g       0.025 g     0.025 g                    butylphenyl)-4,4'-                                                            biphenylenephosphonite)                                                       Other stabilizer                                                                            Irganox 1010 (a                                                                          diethyl 3,5-di-t-butyl-                                                                     Irganox 1222 (a                                                                           Irganox 1222 (a                          product of Ciba-                                                                         4-hydroxybenzylphospho-                                                                     product of Ciba-                                                                          product of Ciba-                         Geigy): 0.025 g                                                                          nate (a product of                                                                          Geigy): 0.025 g                                                                           Geigy): 0.025 g                                     Ciba-Geigy, Irganox                                                           (1222): 0.025 g                                      Rel. soln. viscosity of                                                                     1.18       1.20            --          --                       polycondensate at                                                             addition                                                                      Hue of polycondensate                                                                       nearly colorless                                                                         nearly colorless                                                                            nearly colorless                                                                          nearly colorless           Av. mol. wt. of                                                                             29,900     27,500        28,600      28,600                     polycondensate                                                                Thermogravimetric analysis                                                    T.sub.d       432° C.                                                                           400° C.                                                                              429° C.                                                                            429° C.             T.sub.5       470° C.                                                                           458° C.                                                                              458° C.                                                                            458° C.             T.sub.10      486° C.                                                                           472° C.                                                                              474° C.                                                                            474° C.             After hydrolysis for 30                                                       days at 90° C. and 100%                                                RH                                                                            appearance    colorless and                                                                            colorless and colorless and                                                                             colorless and                            transparent                                                                              transparent   transparent transparent                retension of mol. wt.                                                                       88.7%      89.9%         90.5%       90.5%                      __________________________________________________________________________                  Ex. A-5     Comp. Ex. A-1                                                                             Comp. Ex. A-2                                                                              Comp. Ex.                  __________________________________________________________________________                                                       A-3                        Dihydroxy compound                                                                          bisphenol A bisphenol A bisphenol A  bisphenol A                              22.8 g (0.1 mol %)                                                                        22.8 g (0.1 mol %)                                                                        22.8 g (0.1 mol %)                                                                         22.8 g (0.1 mol %)         Bisaryl carbonate                                                                           diphenyl carbonate                                                                        bisphenyl carbonate                                                                       bisphenyl carbonate                                                                        bisphenyl carbonate                      23.0 g (0.108 mol %)                                                                      23.0 g (0.108 mol %)                                                                      23.0 g (0.108 mol                                                                          23.0 g (0.108 mol %)       Catalyst      4-(4-methylpyrrolidinyl)-                                                                 lithium hydroxide                                                                         lithium carbonate                                                                          tetrabutylammonium                       pyridine    10.sup.-3 mol %                                                                           10.sup.-3 mol %                                                                            bromide                                  2 × 10.sup.-4 mol %                                                                 (based on bisphenol A)                                                                    (based on bisphenol                                                                        10.sup.-3 mol %                          (based on bisphenol A)               (based on bisphenol                                                           A)                         Tetrakis(2,4-di-t-                                                                          0.025 g       --        0.05 g         --                       butylphenyl)-4,4'-                                                            biphenylenephosphonite)                                                       Other stabilizer                                                                            octadecyl 3-(3',5'-d-t-                                                                     --        Irganox 1010 (a product                                                                    Irganox 1010 (a                                                               product                                  butyl-4'-hydroxyphenyl)-                                                                              of Ciba-Geigy): 0.025                                                                      of Ciba-Geigy): 0.05                                                          g                                        propionate; 0.025 g                                             Rel. soln. viscosity of                                                                     1.02          --        0.8          0.9                        polycondensate at                                                             addition                                                                      Hue of polycondensate                                                                       colorless and transparent                                                                 pale-yellow pale-yellow  pale-yellow                Av. mol. wt. of                                                                             23,900      26,500      8,300        9,500                      polycondensate                                                                Thermogravimetric analysis                                                    T.sub.d       420° C.                                                                            375° C.                                                                            306° C.                                                                             310° C.             T.sub.5       460° C.                                                                            414° C.                                                                            360° C.                                                                             383° C.             T.sub.10      468° C.                                                                            430° C.                                                                            395° C.                                                                             400° C.             After hydrolysis for 30                                                       days at 90° C. and 100%                                                RH                                                                            appearance    colorless and transparent                                                                 translucent and many                                                                      failure in molding                                                                         failure in molding                                   white spots                                         retension of mol. wt.                                                                       89.3%       65.3%       70.0%        68.3%                      __________________________________________________________________________

Example B-1

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane, potassiumborohydride (in an amount of 10⁻³ mole % based on the dihydroxy compoundfed) and 214 parts by weight of diphenyl carbonate were fed into areactor and the contents were stirred at 180° C. in a nitrogenatmosphere for one hour. The temperature of the contents was graduallyraised to 250° C., while the pressure of the system was lowered to 2mmHg. The temperature of the contents was further raised and theresulting mixture was reacted at 280° C. in a vacuum of 0.5 mmHg for 2hours to give a polycarbonate. This polycarbonate was nearly colorlessand transparent and had an intrinsic viscosity [η] of 0.438 asdetermined in methylene chloride at 20° C. The average molecular weightMv of the polycarbonate was 24,300 as calculated according to theformula described in Example A-1.

254 g of the polycarbonate thus obtained was mixed with 0.254 g (0.1% byweight based on the polymer) ofbis(2,6-di-t-butyl-4-methylphenyl)Pentaerythritol diphosphite on atumbling blender (mfd. by Matsui Seisakusho, SKB-50) and the obtainedmixture was extruded and pelletized by the use of a twin-screw extruder(HAAKE Buchler Product HBI System 90).

The pelletized composition was evaluated for the heat resistance asdescribed in Example A-1. The decomposition-initiating temperature,T_(d) was 430° C.; the temperature, T₅ was 468° C. and the temperature,T₁₀ was 481° C.

Further, the composition was also evaluated for the resistance tohydrolysis as described in Example A-1. After the lapse of 30 days underthe conditions of 90° C. and 1004% RH (relative humidity), the retentionof the molecular weight was 88.14% based on the initial molecular weightand the resulting sheet was colorless and transparent and no abnormalphenomenon was observed in respect of the external appearance. Theseresults are given in Table 2.

Example B-2

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 0.164 g (2×10⁻²mol) of 2-methylimidazole and 21.4 g (0.1 mol) of diphenyl carbonatewere fed into a reactor. The contents were stirred at 180° C. in anitrogen atmosphere for one hour. The temperature of the contents wasgradually raised to 250° C., while the pressure of the system waslowered to 2 mmHg. At this point of time, 0.025 g (0.1% by weight basedon the whole polycondensate) ofbis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite was addedinto the reactor. At the point of time of this addition, the relativesolution viscosity (polymer concentration: 0.5 g/100 ml, 20° C.,solvent: methylene chloride) presumed from the stirring torque was 1.17,while the one actually determined by the use of a sample of thepolycondensate was 1.18.The temperature of the contents was furtherraised and the contents were reacted at 280° C. in a vacuum of 0.5 mmHgfor 2 hours to give a polycarbonate. This polycarbonate was nearlycolorless and transparent and had an intrinsic viscosity [η] of 0.519 asdetermined in methylene chloride at 20° C. The average molecular weightMv of the polycarbonate was 29,900 as calculated according to theformula described in Example A-1.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior thereof are given in Table 2.

Example B-3

Another polycarbonate composition was prepared in the same manner asthat of Example B-1 except that potassium borohydride was replaced bydimethylamine-borane complex (in an amount of 10⁻² mole % based on thedihydroxyl compound fed). The obtained polycarbonate composition waspelletized and evaluated for the resistances to heat and hydrolysis in asimilar manner to that of Example B-1.The results are given in Table 2.

Example B-4

114 parts by weight (50 mole %) of 2,2-bis(4-hydroxyphenyl)propane, 170parts by weight (50 mole %) of2,2-bis(4-hydroxy-3-t-butylphenyl)propane, 214 parts by weight ofdiphenyl carbonate and 4-dimethylaminopyridine (in an amount of 10⁻²mole % based on the dihydroxy compound fed) were fed into a reactor. Thecontents were reacted under the same conditions as those of Example B-1to give a copolycarbonate.Bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite was addedto the copolycarbonate, the copolycarbonate composition thus obtainedwas pelletized and evaluated for the resistances to heat and hydrolysisin a similar manner to that of Example B-1.The results are given inTable 2.

Example B-5

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 42.1 g (0.1 mol) ofbis(2,4,6-trichlorophenyl) carbonate and 0.0122 g (10⁻⁴ mol) ofdimethylaminopyridine were stirred together at 180° C. in a nitrogenatmosphere for one hour. The temperature of the mixture was raised,while gradually lowering the pressure of the system. When the relativesolution viscosity reached 1.19, 0.025 g ofbis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite was addedto the mixture, and the obtained mixture was further reacted like inExample B-2.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior of the obtained polymer are given inTable 2.

Comparative Example B-1

The polycarbonate prepared in Example B-1 was pelletized without beingblended with bis(2,6B-di-t-butyl-4-methylphenyl)pentaerythritoldiphosphite, and evaluated for the resistances to heat and hydrolysis.The results are given in Table 2.

Comparative Example B-2

Another polycarbonate was prepared in the same manner as that of ExampleB-2 except that a known catalyst, i.e., lithium hydroxide as an alkalimetal hydroxide was used instead of 2-methylimidazole in an amount of10⁻³ mole % based on the 2,2-bis(4-hydroxyphenyl)propane fed and that nobis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite was added.

Although the obtained polymer had an average molecular weight as high as26,500, the polymer was pale-yellow; the thermal decomposition thereofbegan at 375° C. and the weight loss to reach 430° C. was 10%. Further,in the hydrolysis test at 90° C. and 100% RH, the retention of theaverage molecular weight after 30 days was as low as 65.3% and theresulting test sheet was translucent, had many small white spots(partially including voids) all over and was brittle remarkably. Theseresults are given in Table 2.

                                      TABLE 2                                     __________________________________________________________________________           Ex. B-1 Ex. B-2 Ex. B-3 Ex. B-4 Ex. B-5 Comp. Ex.                                                                             Comp. Ex.              __________________________________________________________________________                                                           B-2                    Dihydroxy                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-             compound                                                                             compound                                                                              compound                                                                              compound                                                                              compound                                                                              compound                                                                              compound                                                                              compound                      phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                      propane propane propane propane propane propane propane                                               (50 mole %)/                                                                  2,2-bis(4-                                                                    hydroxy-3-t-                                                                  butyl-phenyl)-                                                                propane (50                                                                   mole %)                                        Bisaryl                                                                              diphenyl                                                                              diphenyl                                                                              diphenyl                                                                              diphenyl                                                                              bis(2,4,6-                                                                            diphenyl                                                                              diphenyl               carbonate                                                                            carbonate                                                                             carbonate                                                                             carbonate                                                                             carbonate                                                                             trichloro-                                                                            carbonate                                                                             carbonate                                                     phenyl)                                                                       carbonate                              Catalyst                                                                             potassium                                                                             2-methyl-                                                                             dimethyl-                                                                             4-dimethyl-                                                                           dimethyl-                                                                             potassium                                                                             lithium                       borohydride                                                                           imidazole                                                                             amine-borane                                                                          aminopyridine                                                                         aminopyridine                                                                         borohydride                                                                           hydroxide                                     complex                                                Phosphite                                                                            bis(2,6-di-t-                                                                         bis(2,6-di-t-                                                                         bis(2,6-di-t-                                                                         bis(2,6-di-t-                                                                         bis(2,6-di-t-                                                                          --      --                    compound                                                                             butyl-4-                                                                              butyl-4-                                                                              butyl-4-                                                                              butyl-4-                                                                              butyl-4-                                      methylphenyl)-                                                                        methylphenyl)-                                                                        methylphenyl)-                                                                        methylphenyl)-                                                                        methylphenyl)-                                pentaerythritol                                                                       pentaerythritol                                                                       pentaerythritol                                                                       pentaerythritol                                                                       pentaerythritol                               diphosphite                                                                           diphosphite                                                                           diphosphite                                                                           diphosphite                                                                           diphosphite                                           (rel. soln.                                                                   visocisty at                                                                  addn.: 1.18)                                                   Hue of nearly  nearly  nearly  nearly  nearly  nearly  pale-yellow            polycondensate                                                                       colorless                                                                             colorless                                                                             colorless                                                                             colorless                                                                             colorless                                                                             colorless                      Av. mol. wt.                                                                         24,300  29,900  23,300  25,000  28,000  24,300  26,500                 of poly-                                                                      condensate                                                                    Thermo-                                                                       gravimetric                                                                   analysis                                                                      T.sub.d                                                                              430° C.                                                                        432° C.                                                                        430° C.                                                                        430° C.                                                                        432° C.                                                                        380° C.                                                                        375° C.         T.sub.5                                                                              468° C.                                                                        470° C.                                                                        467° C.                                                                        469° C.                                                                        470° C.                                                                        415° C.                                                                        414° C.         T.sub.10                                                                             481° C.                                                                        486° C.                                                                        481° C.                                                                        482° C.                                                                        486° C.                                                                        435° C.                                                                        430° C.         After                                                                         hydrolysis                                                                    for 30 days at                                                                90° C. and                                                             100% RH                                                                       appearance                                                                           colorless and                                                                         colorless and                                                                         colorless and                                                                         colorless and                                                                         colorless and                                                                         translucent                                                                           translucent                   transparent                                                                           transparent                                                                           transparent                                                                           transparent                                                                           transparent                            retention of                                                                         88.1%   88.7%   88.0%   91.3%   88.9%   68.0%   65.3%                  mol wt.                                                                       __________________________________________________________________________

Example C-1

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane, potassiumborohydride (in an amount of 10⁻³ mole % based on the dihydroxy compoundfed) and 214 parts by weight of diphenyl carbonate were fed into areactor and the contents were stirred at 180° C. in a nitrogenatmosphere for one hour. The temperature of the contents was graduallyraised to 250° C., while the pressure of the system was lowered to 2mmHg. The temperature of the contents was further raised and theresulting mixture was reacted at 280° C. in a vacuum of 0.5 mmHg for 2hours to give a polycarbonate. This polycarbonate was nearly colorlessand transparent and had an intrinsic viscosity [η] of 0.519 asdetermined in methylene chloride at 20° C. The average molecular weightMv of the polycarbonate was 29,900 as calculated according to theformula described in Example A-1.

254 g of the polycarbonate thus obtained was mixed with 0.254 g (0.1% byweight based on the polymer) ofbis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite and 0.254g (0.1% by weight based on the polymer) of octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate on a tumbling blender (mfd. byMatsui Seisakusho, SKB-50) and the obtained mixture was extruded andpelletized by the use of a twin-screw extruder (HAAKE Buchler ProductHBI System 90).

The pelletized composition was evaluated for the heat resistance asdescribed in Example A-1.The decomposition-initiating temperature, T_(d)was 433° C.; the temperature, T₅ was 472° C.; and the temperature, Ti₁₀was 490° C.

Further, the composition was also evaluated for the resistance tohydrolysis as described in Example A-1.After the lapse of 30 days underthe conditions of 90° C. and 100% RH (relative humidity), the retentionof the molecular weight was 89.8% based on the initial molecular weightand the resulting sheet was colorless and transparent and no abnormalphenomenon was observed in respect of the external appearance.

These results are given in Table 3.

Example C-2

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane was dissolved ina 0.1N aqueous solution of sodium hydroxide, followed by the addition of214 parts by weight of diphenyl carbonate and dichloromethane. Phosgenewas introduced into the obtained mixture while stirring the mixturevigorously. The obtained viscous solution was separated to recover adichloromethane solution. This solution was distilled to remove thedichloromethane to obtain a nearly colorless polycarbonate. Thispolycarbonate was washed with methanol several times, dried and examinedfor the molecular weight in a similar manner to that of Example C-1.Theviscosity-average molecular weight (Mv) thereof was 28,000.In a similarmanner to that of Example C-1, a mixture of the polycarbonate thusobtained with bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritoldiphosphite and octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate was pelletized and evaluatedfor the resistances to heat and hydrolysis. The results are given inTable 3.

Example C-3

Another polycarbonate was prepared in the same manner as that of ExampleC-1 except that potassium borohydride was replaced by4-dimethylaminopyridine (in an amount of 10⁻² mole % based on thedihydroxy compound fed). In a similar manner to that of Example C-1, amixture of the polycarbonate thus obtained withbis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite andoctadecyl 3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate waspelletized and evaluated for the resistances to heat and hydrolysis. Theresults are given in Table 3.

Example C-4

A copolycarbonate was prepared in the same manner as that of Example C-1except that 114 parts by weight (50 mole %) of2,2-bis(4-hydroxyphenyl)propane and 170 parts by weight (50 mole %) of2,2-bis(4-hydroxy-3-t-butylphenyl)propane were used instead of2,2-bis(4-hydroxyphenyl)propane, and that imidazole (in an amount of10⁻² mole % based on the dihydroxy compound fed) was used instead ofpotassium borohydride. A mixture of the copolycarbonate thus obtainedwith bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite andoctadecyl 3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate waspelletized and evaluated For the resistances to heat and hydrolysis in asimilar manner to that of Example C-1.The results are given in Table 3.

Comparative Example C-1

The polycarbonate prepared in Example C-1 was pelletized without beingblended with bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritoldiphosphite or octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, and evaluated for theresistances to heat and hydrolysis. The results are given in Table 3.

                                      TABLE 3                                     __________________________________________________________________________                  Ex. C-1   Ex. C-2   Ex. C-3  Ex. C-4    Comp. Ex.               __________________________________________________________________________                                                          C-1                     Dihydroxy compound                                                                          2,2-bis(4-hydroxy-                                                                      2,2-bis(4-hydroxy-                                                                      2,2-bis(4-hydroxy-                                                                     2,2-bis(4-hydroxy-                                                                       2,2-bis(4-hydroxy-                    phenyl)propane                                                                          phenyl)propane                                                                          phenyl)propane                                                                         phenyl)propane                                                                           phenyl)propane                        254 g     254 g     254 g    mole %)/2,2-bis(4-                                                                       254 g                                                              hydroxy-3-t-butyl-                                                            phenyl)propane (50                                                            mole %)                                                                       282 g                              Bis(2,6-di-t-butyl-4-                                                                       0.254 g   0.254 g   0.254 g  0.282 g      --                    methylphenyl)penta-                                                                         (0.1% by wt.)                                                                           (0.1% by wt.)                                                                           (0.1% by wt.)                                                                          (0.1% by wt.)                      erythritol diphosphite                                                        Octadecyl 3-(3',5'-di-                                                                      0.254 g   0.254 g   0.254 g  0.282 g      --                    t-butyl-4'-hydroxy-                                                                         (0.1% by wt.)                                                                           (0.1% by wt.)                                                                           (0.1% by wt.)                                                                          (0.1% by wt.)                      phenyl)propionate                                                             Hue of polycondensate                                                                       nearly colorless                                                                        nearly colorless                                                                        nearly colorless                                                                       colorless  nearly colorless        Av. mol. wt. of                                                                             29,900    28,000    28,200   25,200     29,900                  polycondensate                                                                Thermogravimetric analysis                                                    T.sub.d       433° C.                                                                          432° C.                                                                          433° C.                                                                         420° C.                                                                           375° C.          T.sub.5       472° C.                                                                          472° C.                                                                          472° C.                                                                         464° C.                                                                           414° C.          T.sub.10      490° C.                                                                          490°  C.                                                                         491° C.                                                                         480° C.                                                                           430° C.          After hydrolysis for 30 days                                                  at 90° C. and 100% RH                                                  appearance    colorless and                                                                           colorless and                                                                           colorless and                                                                          colorless and                                                                            translucent                           transparent                                                                             transparent                                                                             transparent                                                                            transparent                        retention of mol. wt. (%)                                                                   89.8%     89.5%     89.6%    90.2%      67.3%                   __________________________________________________________________________

Example D-1

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane, potassiumborohydride (in an amount of 10⁻³ mole % based on the dihydroxy compoundfed) and 214 parts by weight of diphenyl carbonate were fed into areactor and the contents were stirred at 180° C. in a nitrogenatmosphere for one hour. The temperature of the contents was graduallyraised to 250° C., while the pressure of the system was lowered to 2mmHg. The temperature of the contents was further raised and theresulting mixture was reacted at 280° C. in a vacuum of 0.5 mmHg for 2hours to give a polycarbonate. This carbonate was nearly colorless andtransparent and had an intrinsic viscosity [η] of 0.438 as determined inmethylene chloride at 20° C. The average molecular weight Mv of thepolycarbonate was 24,300 as calculated according to the formuladescribed in Example A-1.

254 g of the polycarbonate thus obtained was mixed with 0.254 g (0.1% byweight based on the polymer) of tris(2,4-di-t-butylphenyl)phosphite and0.254 g (0.1% by weight based on the polymer) of octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate on a tumbling blender (mfd. byMatusi Seisakusho, SKB-50) and the obtained mixture was extruded andpelletized by the use of a twin-screw extruder (HAAKE Buchler ProductHBI System 90).

The pelletized composition was evaluated for the heat resistance asdescribed in Example A-1.The decomposition-initiating temperature, T_(d)was 429° C.; the temperature, T₅ was 466° C.; and the temperature, T₁₀was 480° C.

Further, the composition was also evaluated for the resistance tohydrolysis as described in Example A-1.After the lapse of 30 days underthe conditions of 90° C. and 100% RH (relative humidity), the retentionof the molecular weight was 87.8% based on the initial molecular weightand the resulting sheet was colorless and transparent and no abnormalphenomenon was observed with respect to the external appearance.

These results are given in Table 4.

Example D-2

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 0.164 g (2×10⁻²mol) of 2-methylimidazole and 21.4 g (0.1 mol) of diphenyl carbonatewere fed into a reactor. The contents were stirred at 180° C. in anitrogen atmosphere for one hour. The temperature of the contents wasgradually raised to 250° C., while the pressure of the system waslowered to 2 mmHg. At this point of time,tris(2,4-di-t-butylphenyl)phosphite and octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate were added to the reactor eachin an amount of 0.025 g (0.1% by weight based on the wholepolycondensate). At the point of this addition, the relative solutionviscosity (polymer concentration: 0.5 g/100 ml, 20° C., solvent:methylene chloride) presumed from the stirring torque was 1.17, whilethe one actually determined by the use of a sample of the polycondensatewas 1.18. The temperature of the contents was further raised and thecontents were reacted at 280° C. in a vacuum of 0.5 mmHg for 2 hours togive a polycarbonate. This polycarbonate was nearly colorless andtransparent and had an intrinsic viscosity [η] of 0.492 as determined inmethylene chloride at 20° C. The average molecular weight Mv of thepolycarbonate was 28,000 as calculated according to the formuladescribed in Example A-1.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior of the obtained polycarbonate are givenin Table 4.

Example D-3

Another polycarbonate was prepared in the same manner as that of ExampleD-1 except that potassium borohydride was replaced bydimethylamine-borane complex (in an amount of 10⁻² mole % based on thedihydroxy compound fed). A mixture of the obtained polycarbonate withtris(2,4-di-t-butylphenyl)phosphite and octadecyl3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate was pelletized andevaluated for the resistances to heat and hydrolysis in a similar mannerto that of Example D-1.The results are given in Table 4.

Example D-4

114 parts by weight (50 mole %) of 2,2-bis(4-hydroxyphenyl)propane, 170parts by weight (50 mole %) of2,2-bis(4-hydroxy-3-t-butylphenyl)propane, 214 parts by weight ofdiphenyl carbonate and 4-dimethylaminopyridine (in an amount of 10⁻²mole % based on the dihydroxy compound fed) were fed into a reactor. Thecontents were reacted under the same conditions as those of Example D-1to give a copolycarbonate. A mixture of the obtained copolycarbonatewith tris(2,4-di-t-butylphenyl)phosphite and octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)Propionate was pelletized and evaluatedfor the resistances to heat and hydrolysis in a similar manner to thatof Example D-1.The results are given in Table 4.

Example D-5

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 42.1 g (0.1 mol) ofbis(2,4,6-trichlorophenyl)carbonate and 0.0122 g (10⁻⁴ mol) ofdimethylaminopyridine were stirred together at 180° C. in a nitrogenatmosphere for one hour. The temperature of the mixture was raised,while gradually lowering the pressure of the system. When the relativesolution viscosity reached 1.19, tris(2,4-di-t-butylphenyl)phosphite andoctadecyl 3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate were added tothe mixture each in an amount of 0.025 g, and the obtained mixture wasfurther reacted like in Example D-2.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior of the obtained polymer are given inTable 4.

Comparative Example D-1

The polycarbonate prepared in Example D-1 was pelletized without beingblended with tris(2,4-di-t-butylphenyl)phosphite or octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, and evaluated for theresistances to heat and hydrolysis. The results are given in Table 4.

Comparative Example D-2

Another polycarbonate was prepared in the same manner as that of ExampleD-2 except that a known catalyst for comparison, i.e., lithium hydroxideas an alkali metal hydroxide was used in an amount of 10⁻³ mole % basedon the 2,2-bis(4-hydroxyphenyl)propane fed and that neithertris(2,4-di-t-butylphenyl) phosphite nor octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate was added.

Although the obtained polymer had an average molecular weight as high as26,500, the polymer was pale-yellow: the thermal decomposition thereofbegan at 375° C. and the weight loss to reach 430° C. was 10%. Further,in the hydrolysis test at 90° C. and 100% RH, the retention of theaverage molecular weight after 30 days was as low as 65.3% and theresulting test sheet was translucent, had many small white spots(partially including voids) all over and was brittle remarkably. Theseresults are given in Table 4.

                                      TABLE 4                                     __________________________________________________________________________           Ex. D-1 Ex. D-2 Ex. D-3 Ex. D-4 Ex. D-5 Comp. Ex.                                                                             Comp. Ex.              __________________________________________________________________________                                                           D-2                    Dihydroxy                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-             compound                                                                             hydroxy-                                                                              hydroxy-                                                                              hydroxy-                                                                              hydroxy-                                                                              hydroxy-                                                                              hydroxy-                                                                              hydroxy-                      phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                      propane propane propane propane propane propane propane                                               (50 mole %)/                                                                  2,2-bis(4-                                                                    hydroxy-3-t-                                                                  butyl-phenyl)-                                                                propane (50                                                                   mole %)                                        Bisaryl                                                                              diphenyl                                                                              diphenyl                                                                              diphenyl                                                                              diphenyl                                                                              bis(2,4,6-                                                                            diphenyl                                                                              diphenyl               carbonate                                                                            carbonate                                                                             carbonate                                                                             carbonate                                                                             carbonate                                                                             trichloro-                                                                            carbonate                                                                             carbonate                                                     phenyl)                                                                       carbonate                              Catalyst                                                                             potassium                                                                             2-methyl-                                                                             dimethyl-                                                                             4-dimethyl-                                                                           dimethyl-                                                                             potassium                                                                             lithium                       borohydride                                                                           imidazole                                                                             amine-borane                                                                          aminopyridine                                                                         aminopyridine                                                                         borohydride                                                                           hydroxide                                     complex                                                Phosphite                                                                            tris(2,4-di-t-                                                                        tris(2,4-di-t-                                                                        tris(2,4-di-t-                                                                        tris(2,4-di-t-                                                                        tris(2,4-di-t-                                                                         --      --                    compound                                                                             butylphenyl)-                                                                         butylphenyl)-                                                                         butylphenyl)-                                                                         butylphenyl)-                                                                         butylphenyl)-                                 phosphite                                                                             phosphite                                                                             phosphite                                                                             phosphite                                                                             phosphite                              Hindered                                                                             octadecyl 3-                                                                          octadecyl 3-                                                                          octadecyl 3-                                                                          octadecyl 3-                                                                          octadecyl 3-                                                                           --      --                    phenol (3',5'-di-t-butyl-                                                                    (3',5'-di-t-butyl-                                                                    (3',5' -di-t-butyl-                                                                   (3',5'-di-t-butyl-                                                                    (3',5'-di-t-butyl-                     compound                                                                             4'-hydroxy-                                                                           4'-hydroxy-                                                                           4'-hydroxy-                                                                           4'-hydroxy-                                                                           4'-hydroxy-                                   phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                      propionate                                                                            propionate                                                                            propionate                                                                            propionate                                                                            propionate                                            (rel. soln.                                                                   viscosity at                                                                  addn.: 1.18)                                                   Hue of nearly  nearly  nearly  nearly  nearly  nearly  pale-yellow            polycondensate                                                                       colorless                                                                             colorless                                                                             colorless                                                                             colorless                                                                             colorless                                                                             colorless                      Av. mol. wt.                                                                         24,300  28,000  24,500  25,000  28,000  24,300  26,500                 of poly-                                                                      condensate                                                                    Thermo-                                                                       gravimetric                                                                   analysis                                                                      T.sub.d                                                                              429° C.                                                                        430° C.                                                                        430° C.                                                                        430° C.                                                                        432° C.                                                                        380° C.                                                                        375° C.         T.sub.5                                                                              466° C.                                                                        468° C.                                                                        467° C.                                                                        469° C.                                                                        470° C.                                                                        415° C.                                                                        414° C.         T.sub.10                                                                             480° C.                                                                        486° C.                                                                        481° C.                                                                        482° C.                                                                        486° C.                                                                        435° C.                                                                        430° C.         After                                                                         hydrolysis                                                                    for 30 days                                                                   at 90° C.                                                              and 100% RH                                                                   appearance                                                                           colorless and                                                                         colorless and                                                                         colorless and                                                                         colorless and                                                                         colorless and                                                                         translucent                                                                           translucent                   transparent                                                                           transparent                                                                           transparent                                                                           transparent                                                                           transparent                            retention                                                                            87.8%   88.2%   88.0%   90.5%   88.9%   68.0%   65.3%                  of mol. wt.                                                                   __________________________________________________________________________

Example E-1

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane, potassiumborohydride (in an amount of 10⁻³ mole % based on the dihydroxy compoundfed) and 214 parts by weight of diphenyl carbonate were fed into areactor. The contents were stirred at 180° C. in a nitrogen atmospherefor one hour. The temperature of the contents was gradually raised to250° C., while the pressure of the system was lowered to 2 mmHg. Thetemperature of the contents was further raised and the contents werereacted at 280° C. in a vacuum of 0.5 mmHg for 2 hours to give apolycarbonate. This polycarbonate was nearly colorless and transparentand had an intrinsic viscosity [η] of 0.434 as determined in methylenechloride at 20° C. The average molecular weight Mv of the polycarbonatewas 24,000 as calculated according to the formula described in ExampleA-1.

254 g of the polycarbonate thus prepared was mixed with 0.254 g (0.1% byweight based on the polymer) of tris(2,4-di-t-butylphenyl)phosphite on atumbling blender (mfd. by Matsui Seisakusho, SKB-50) and the obtainedmixture was extruded and pelletized by the use of a twin-screw extruder(HAAKE Buchler Product HBI System 90). The pelletized composition wasevaluated for the heat resistance as described in Example A-1.Thedecomposition-initiating temperature, T_(d) was 426° C.; thetemperature, T₅ was 465° C. and the temperature, T₁₀ was 478° C.

Further, the above composition was also evaluated for the resistance tohydrolysis as described in Example A-1.After the lapse of 30 days underthe conditions of 90° C. and 100% RH (relative humidity), the retentionof the molecular weight was 86.3% based on the initial molecular weightand the resulting sheet was colorless and transparent and no abnormalphenomenon was observed with respect to the external appearance.

These results are given in Table 5.

Example E-2

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 0.164 g (2×10⁻²mol) of 2-methylimidazole and 21.4 g (0.1 mol) of diphenyl carbonatewere fed into a reactor. The contents were stirred at 180° C. in anitrogen atmosphere for one hour. The temperature of the contents wasgradually raised to 250° C., while the pressure of the system waslowered to 2 mmHg. At this point of time, 0.025 g (0.1% by weight basedon the whole polycondensate) of tris(2,4-di-t-butylphenyl)phosphite wasadded to the reactor. At the point of time of this addition, therelative solution viscosity (polymer concentration: 0.5 g/100 ml, 20°C., solvent: methylene chloride) presumed from the stirring torque was1.17, while the one actually determined by the use of a sample of thepolycondensate was 1.18.The temperature of the contents was furtherraised and the contents were reacted at 280° C. in a vacuum of 0.5 mmHgfor 2 hours to give a polycarbonate. This polycarbonate was nearlycolorless and transparent and had an intrinsic viscosity [η] of 0.489 asdetermined in methylene chloride at 20° C. The average molecular weightMv of the polycarbonate was 27,800 as calculated according to theformula described in Example A-1.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior of the polycarbonate are given in Table5.

Example E-3

Another polycarbonate was prepared in the same manner as that of ExampleE-1 except what dimethylamine-borane complex (in an amount of 10⁻² molebased on the dihydroxy compound fed) was used instead of potassiumborohydride. In a similar manner to that of Example E-1, a mixture ofthe polycarbonate thus obtained withtris(2,4-di-t-butyl-phenyl)phosphite was pelletized and evaluated forthe resistances to heat and hydrolysis. The results are given in Table5.

Example E-4

114 parts by weight (50 mole 4) of 2,2-bis(4-hydroxyphenyl)propane, 170parts by weight (50 mole %) of2,2-bis(4-hydroxy-3-t-butylphenyl)propane, 214 parts by weight ofdiphenyl carbonate and 4-dimethylaminopyridine (in an amount of 10⁻²mole % based on the dihydroxy compound fed) were fed into a reactor. Thecontents were reacted under the same conditions as those of Example E-1to give a copolycarbonate. In a similar manner to that of Example E-1, amixture of the copolycarbonate thus obtained withtris(2,4-di-t-butylphenyl)phosphite was pelletized and evaluated for theresistances to heat and hydrolysis. The results are given in Table 5.

Example E-5

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 42.1 g (0.1 mol) ofbis(2,4,6-trichlorophenyl)carbonate and 0.0122 g (10⁻⁴ mol) ofdimethylaminopyridine were stirred together at 180° C. in a nitrogenatmosphere for one hour. The temperature of the mixture was raised,while gradually lowering the pressure of the system. When the relativesolution viscosity reached 1.19, 0.025 g oftris(2,4-di-t-butylphenyl)phosphite was added to the reaction mixture,and the obtained mixture was further reacted like in Example E-2 to givea polycarbonate.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior thereof are given in Table 5.

Comparative Example E-1

The polycarbonate prepared in Example E-1 was pelletized without beingblended with tris(2,4-di-t-butylphenyl)phosphite and evaluated for theresistances to heat and hydrolysis. The results are given in Table 5.

Comparative Example E-2

Another polycarbonate was prepared in the same manner as that of ExampleE-2 except that a known catalyst for comparison, i.e., lithium hydroxideas an alkali metal hydroxide was used in an amount of 10⁻³ mole % basedon the 2,2-bis(4-hydroxyphenyl)propane used and that notris(2,4-di-t-butylphenyl)phosphite was added.

Although the obtained polymer had an average molecular weight as high as26,500, the polymer was pale-yellow; the thermal decomposition thereofbegan at 375° C.; and the weight loss to reach 430° C. was 10%. Further,in the hydrolysis test at 90° C. and 100% RH, the retention of theaverage molecular weight after 30 days was as low as 65.3% and theresulting test sheet was translucent, had many white spots (partiallyincluding voids) all over and was brittle remarkably. These results aregiven in Table 5.

                                      TABLE 5                                     __________________________________________________________________________           Ex. E-1 Ex. E-2 Ex. E-3 Ex. E-4 Ex. E-5 Comp. Ex.                                                                             Comp. Ex.              __________________________________________________________________________                                                           E-2                    Dihydroxy                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-             compound                                                                             hydroxy-                                                                              hydroxy-                                                                              hydroxy-                                                                              hydroxy-                                                                              hydroxy-                                                                              hydroxy-                                                                              hydroxy-                      phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                      propane propane propane propane propane propane propane                                               (50 mole %)/                                                                  2,2-bis(4-                                                                    hydroxy-3-t-                                                                  butyl-phenyl)-                                                                propane (50                                                                   mole %)                                        Bisaryl                                                                              diphenyl                                                                              diphenyl                                                                              diphenyl                                                                              diphenyl                                                                              bis(2,4,6-                                                                            diphenyl                                                                              diphenyl               carbonate                                                                            carbonate                                                                             carbonate                                                                             carbonate                                                                             carbonate                                                                             trichloro-                                                                            carbonate                                                                             carbonate                                                     phenyl)                                                                       carbonate                              Catalyst                                                                             potassium                                                                             2-methyl-                                                                             dimethyl-                                                                             4-dimethyl-                                                                           dimethyl-                                                                             potassium                                                                             lithium                       borohydride                                                                           imidazole                                                                             amine-borane                                                                          aminopyridine                                                                         aminopyridine                                                                         borohydride                                                                           hydroxide                                     complex                                                Phosphite                                                                            tris(2,4-di-t-                                                                        tris(2,4-di-t-                                                                        tris(2,4-di-t-                                                                        tris(2,4-di-t-                                                                        tris(2,4-di-t-                                                                         --      --                    compound                                                                             butyl-  butyl-  butyl-  butyl-  butyl-                                        phenyl  phenyl  phenyl  phenyl  phenyl                                        phosphite)                                                                            phosphite)                                                                            phosphite)                                                                            phosphite)                                                                            phosphite)                                            (rel. soln.                                                                   viscosity at                                                                  addn.: 1.18)                                                   Hue of nearly  nearly  nearly  nearly  nearly  nearly  pale-yellow            polycondensate                                                                       colorless                                                                             colorless                                                                             colorless                                                                             colorless                                                                             colorless                                                                             colorless                      Av. mol. wt.                                                                         24,000  27,800  24,000  25,000  27,600  24,300  26,500                 of poly-                                                                      condensate                                                                    Thermo-                                                                       gravimetric                                                                   analysis                                                                      T.sub.d                                                                              426° C.                                                                        429° C.                                                                        430° C.                                                                        430° C.                                                                        430° C.                                                                        380° C.                                                                        375° C.         T.sub.5                                                                              465° C.                                                                        465° C.                                                                        467° C.                                                                        469° C.                                                                        469° C.                                                                        415° C.                                                                        414° C.         T.sub.10                                                                             478° C.                                                                        484° C.                                                                        481° C.                                                                        482° C.                                                                        484° C.                                                                        435° C.                                                                        430° C.         After                                                                         hydrolysis                                                                    for 30 days at                                                                90° C. and                                                             100% RH                                                                       appearance                                                                           colorless and                                                                         colorless and                                                                         colorless and                                                                         colorless and                                                                         colorless and                                                                         translucent                                                                           translucent                   transparent                                                                           transparent                                                                           transparent                                                                           transparent                                                                           transparent                            retention of                                                                         86.3%   87.1%   88.0%   90.1%   88.7%   68.0%   65.3%                  mol wt.                                                                       __________________________________________________________________________

Example F-1

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane, potassiumborohydride (in an amount of 10⁻³ mole % based on the dihydroxy compoundfed) and 214 parts by weight of diphenyl carbonate were fed into areactor. The contents were stirred at 180° C. in a nitrogen atmospherefor one hour. The temperature of the contents was gradually raised to250° C., while the pressure of the system was lowered to 2 mmHg. Thetemperature of the contents was further raised and the contents werereacted at 280° C. in a vacuum of 0.5 mmHg for 2 hours to give apolycarbonate. This polycarbonate was nearly colorless and transparentand had an intrinsic viscosity [η] of 0.438 as determined in methylenechloride at 20° C. The average molecular weight Mv of the polycarbonatewas 24,300 as calculated according to the formula described in ExampleA-1.

254 g of the polycarbonate thus prepared was mixed withtris(4-nonylphenyl)phosphite and octadecyl3-(3',5'-di-t-butyl-4'-hydroxyphenyl)Propionate each in an amount of0.254 g (0.1% by weight based on the polymer) on a tumbling blender(mfd. by Matsui Seisakusho, SKB-50) and the obtained mixture wasextruded and pelletized by the use of a twin-screw extruder (HAAKEBuchler Product HBI System 90).

The pelletized composition was evaluated for the heat resistance asdescribed in Example A-1.The decomposition-initiating temperature, T_(d)was 430° C.; the temperature, T₅ was 467° C.; and the temperature, T₁₀was 481° C.

Further, the above composition was also evaluated for the resistance tohydrolysis as described in Example A-1.After the lapse of 30 days underthe conditions of 90° C. and 100% RH (relative humidity), the retentionof the molecular weight was 88.0% based on the initial molecular weightand the resulting sheet was colorless and transparent and no abnormalphenomenon was observed in respect of the external appearance.

These results are given in Table 6.

Example F-2

22.8 g (0.1-mol) of 2,2-bis(4-hydroxyphenyl)propane, 0.164 g (2×10⁻²mol) of 2-methylimidazole and 21.4 g (0.1 mol) of diphenyl carbonatewere fed into a reactor. The contents were stirred at 180° C. in anitrogen atmosphere for one hour. The temperature of the contents wasgradually raised to 250° C., while the pressure of the system waslowered to 2 mmHg. At this point of time, tris(4-nonylphenyl)phosphiteand octadecyl 3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate wereadded into the reactor each in an amount of 0.025 g (0.1% by weightbased on the whole polycondensate). At the point of time of thisaddition, the relative solution viscosity (polymer concentration: 0.5g/100 ml, 20° C., solvent: methylene chloride) presumed from thestirring torque was 1.17, while the one actually determined by the useof a sample of the polycondensate was 1.18.The temperature of thecontents was further raised and the contents were reacted at 280° C. ina vacuum of 0.5 mmHg for 2 hours to give a polycarbonate. Thispolycarbonate was nearly colorless and transparent and had an intrinsicviscosity [η] of 0.519 as determined in methylene chloride at 20° C. Theaverage molecular weight Mv of the polycarbonate was 29,900 ascalculated according to the formula described in Example A-1.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior of the polycarbonate are given in Table6.

Example F-3

Another polycarbonate was prepared in the same manner as that of ExampleF-1 except that dimethylamine-borane complex (in an amount of 10⁻² mole% based on the dihydroxy compound fed) was used instead of potassiumborohydride. In a similar manner to that of Example F-1, a mixture ofthe polycarbonate thus obtained with tris(4-nonylphenyl)phosphite andoctadecyl 3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate waspelletized and evaluated for the resistances to heat and hydrolysis. Theresults are given in Table 6.

Example F-4

114 parts by weight (50 mole %) of 2,2-bis(4-hydroxyphenyl)propane, 170parts by weight (50 mole %) of2,2-bis(4-hydroxy-3-t-butylphenyl)propane, 214 parts by weight ofdiphenyl carbonate and 4-dimethylaminopyridine (in an amount of 10⁻²mole % based on the dihydroxy compound fed) were fed into a reactor. Thecontents were reacted under the same conditions as those of Example F-1to give a copolycarbonate. In a similar manner to that of Example F-1, amixture of the copolycarbonate thus obtained withtris(4-nonylphenyl)phosphite and octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate was pelletized and evaluatedfor the resistances to heat and hydrolysis. The results are given inTable 6.

Example F-5

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 42.1 g (0.1 mol) ofbis(2,4,6-trichlorophenyl)carbonate and 0.0122 g (10⁻⁴ mol) ofdimethylaminopyridine were stirred together at 180° C. in a nitrogenatmosphere for one hour. The temperature of the mixture was raised,while gradually lowering the pressure of the system. When the relativesolution viscosity reached 1.19, tris(4-nonylphenyl)phosphite andoctadecyl 3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate were added tothe reaction mixture each in an amount of 0.025 g, and the obtainedmixture was further reacted like in Example F-2 to give a polycarbonate.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior thereof are given in Table 6.

Comparative Example F-1

The polycarbonate prepared in Example F-1 was pelletized without beingblended with tris(4-nonylphenyl)phosphite or octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate and evaluated for theresistances to heat and hydrolysis. The results are given in Table 6.

Comparative Example F-2

Another polycarbonate was prepared in the same manner as that of ExampleF-2 except that a known catalyst for comparison, i.e., lithium hydroxideas an alkali metal hydroxide was used in an amount of 10⁻³ mole % basedon the 2,2-bis(4-hydroxyphenyl)propane used and that neithertris(4-nonylphenyl)phosphite nor octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate was added.

Although the obtained polymer had an average molecular weight as high as26,500, the polymer was pale-yellow; the thermal decomposition thereofbegan at 375° C. and the weight loss to reach 430° C. was 10%. Further,in the hydrolysis test at 90° C. and 100% RH, the retention of theaverage molecular weight after 30 days was as low as 65.3% and theresulting test sheet was translucent, had many white spots (partiallyincluding voids) all over and was brittle remarkably. These results aregiven in Table 6.

                                      TABLE 6                                     __________________________________________________________________________           Ex. F-1 Ex. F-2 Ex. F-3 Ex. F-4 Ex. F-5 Comp. Ex.                                                                             Comp. Ex.              __________________________________________________________________________                                                           F-2                    Dihydroxy                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-                                                                            2,2-bis(4-             compound                                                                             hydroxy-                                                                              hydroxy-                                                                              hydroxy-                                                                              hydroxy-                                                                              hydroxy-                                                                              hydroxy-                                                                              hydroxy-                      phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                      propane propane propane propane propane propane propane                                               (50 mole %)/                                                                  2,2-bis(4-                                                                    hydroxy-3-t-                                                                  butyl-phenyl)-                                                                propane (50                                                                   mole %)                                        Bisaryl                                                                              diphenyl                                                                              diphenyl                                                                              diphenyl                                                                              diphenyl                                                                              bis(2,4,6-                                                                            diphenyl                                                                              diphenyl               carbonate                                                                            carbonate                                                                             carbonate                                                                             carbonate                                                                             carbonate                                                                             trichloro-                                                                            carbonate                                                                             carbonate                                                     phenyl)                                                                       carbonate                              Catalyst                                                                             potassium                                                                             2-methyl-                                                                             dimethyl-                                                                             4-dimethyl-                                                                           dimethyl-                                                                             potassium                                                                             lithium                       borohydride                                                                           imidazole                                                                             amine-borane                                                                          aminopyridine                                                                         aminopyridine                                                                         borohydride                                                                           hydroxide                                     complex                                                Phosphite                                                                            tris(4-nonyl-                                                                         tris(4-nonyl-                                                                         tris(4-nonyl-                                                                         tris(4-nonyl-                                                                         tris(4-nonyl-                                                                          --      --                    compound                                                                             phenyl  phenyl  phenyl  phenyl  phenyl                                        phosphite)                                                                            phosphite)                                                                            phosphite)                                                                            phosphite)                                                                            phosphite)                             Hindered                                                                             octadecyl 3-                                                                          octadecyl 3-                                                                          octadecyl 3-                                                                          octadecyl 3-                                                                          octadecyl 3-                                                                           --      --                    phenol (3',5'-di-t-butyl-                                                                    (3',5'-di-t-butyl-                                                                    (3',5' -di-t-butyl-                                                                   (3',5'-di-t-butyl-                                                                    (3',5'-di-t-butyl-                     compound                                                                             4'-hydroxy-                                                                           4'-hydroxy-                                                                           4'-hydroxy-                                                                           4'-hydroxy-                                                                           4'-hydroxy-                                   phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                                                              phenyl)-                                      propionate                                                                            propionate                                                                            propionate                                                                            propionate                                                                            propionate                                            (rel. soln.             (rel. soln.                                           viscosity at            viscosity at                                          addn.: 1.18)            addn: 1.19)                            Hue of nearly  nearly  nearly  nearly  nearly  nearly  pale-yellow            polycondensate                                                                       colorless                                                                             colorless                                                                             colorless                                                                             colorless                                                                             colorless                                                                             colorless                      Av. mol. wt.                                                                         24,300  29,900  23,300  25,000  28,000  24,300  26,500                 of poly-                                                                      condensate                                                                    Thermo-                                                                       gravimetric                                                                   analysis                                                                      T.sub.d                                                                              430° C.                                                                        432° C.                                                                        430° C.                                                                        430° C.                                                                        432° C.                                                                        380° C.                                                                        375° C.         T.sub.5                                                                              467° C.                                                                        470° C.                                                                        467° C.                                                                        469° C.                                                                        470° C.                                                                        415° C.                                                                        414° C.         T.sub.10                                                                             480° C.                                                                        486° C.                                                                        481° C.                                                                        482° C.                                                                        486° C.                                                                        435° C.                                                                        430° C.         After                                                                         hydrolysis                                                                    for 30 days                                                                   at 90° C.                                                              and 100% RH                                                                   appearance                                                                           colorless and                                                                         colorless and                                                                         colorless and                                                                         colorless and                                                                         colorless and                                                                         translucent                                                                           translucent                   transparent                                                                           transparent                                                                           transparent                                                                           transparent                                                                           transparent                            retention                                                                            88.0%   88.6%   88.0%   91.3%   88.3%   68.0%   65.3%                  of mol. wt.                                                                   __________________________________________________________________________

Example G-1

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane, potassiumborohydride (in an amount of 10⁻³ mole % based on the dihydroxy compoundfed) and 214 parts by weight of diphenyl carbonate were fed into areactor. The contents were stirred at 180° C. in a nitrogen atmospherefor one hour. The temperature of the contents was gradually raised to250° C., while the pressure of the system was lowered to 2 mmHg. Thetemperature of the contents was further raised and the contents werereacted at 280° C. in a vacuum of 0.5 mmHg for 2 hours to give apolycarbonate. This polycarbonate was nearly colorless and transparentand had an intrinsic viscosity [η] of 0.488 as determined in methylenechloride at 20° C. The average molecular weight Mv of the polycarbonatewas 24,300 as calculated according to the formula described in ExampleA-1.

254 g of the polycarbonate thus prepared was mixed with 0.254 g (0.1% byweight based on the polymer) of tridecyl phosphite on a Tumbling blender(mfd. by Matsui Seisakusho, SKB-50) and the obtained mixture wasextruded and pelletized by the use of a twin-screw extruder (HAAKEBuchler Product HBI System 90). The pelletized composition was evaluatedfor the head resistance as described in Example A-1. Thedecomposition-initiating temperature, T_(d) was 425° C.; thetemperature, T₅ was 458° C.; and the temperature, T₁₀ was 471° C.

Further, the above composition was also evaluated for the resistance tohydrolysis as described in Example A-1. After the lapse of 30 days underthe conditions of 90° C. and 100% RH (relative humidity), the retentionof the molecular weight was 87.9% based on the initial molecular weightand the resulting sheet was colorless and transparent and no abnormalphenomenon was observed in respect of the external appearance.

These results are given in Table 7.

Example G-2

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 0.164 g (2×10⁻²mol) of 2-methylimidazole and 21.4 g (0.1 mol) of diphenyl carbonatewere fed into a reactor. The contents were stirred at 180° C. in anitrogen atmosphere for one hour. The temperature of the contents wasgradually raised to 250° C., while the pressure of the system waslowered to 2 mmHg. At this point of time, 0.025 g (0.1% by weight basedon the whole polycondensate) of tridecyl phosphite was added into thereactor. At the point of time of this addition, the relative solutionviscosity (polymer concentration: 0.5 g/100 ml, 20° C., solvent:methylene chloride) presumed from the stirring torque was 1.17, whilethe one actually determined by the use of a sample of the polycondensatewas 1.18. The temperature of the contents was further raised and thecontents were reacted at 280° C. in a vacuum of 0.5 mmHg for 2 hours togive a polycarbonate. This polycarbonate was nearly colorless andtransparent and had an intrinsic viscosity [η] of 0.475 as determined inmethylene chloride at 20° C. The average molecular weight Mv of thepolycondensate was 26,800 as calculated according to the formuladescribed in Example A-1.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior of the polycarbonate are given in Table7.

Example G-3

Another polycarbonate was prepared in the same manner as that of ExampleG-1 except that dimethylamine-borane complex (in an amount of 10⁻² molebased on the dihydroxy compound fed) was used instead of potassiumborohydride. In a similar manner to that of Example G-1, a mixture ofthe polycarbonate thus obtained with tridecyl phosphite was pelletizedand evaluated for the resistances to heat and hydrolysis. The resultsare given in Table 7.

Example G-4

114 parts by weight (50 mole %) of 2,2-bis(4-hydroxyphenyl)propane, 170parts by weight (50 mole %) of2,2-bis(4-hydroxy-3-t-butylphenyl)propane, 214 parts by weight ofdiphenyl carbonate and 4-dimethylaminopyridine (in an amount of 10⁻²mole % based on the dihydroxy compound fed) were fed into a reactor. Thecontents were reacted under The same conditions as those of Example G-1to give a copolycarbonate. In a similar manner to that of Example G-1, amixture of the copolycarbonate thus obtained with tridecyl phosphite waspelletized and evaluated for the resistances to heat and hydrolysis. Theresults are given in Table 7.

Example G-5

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 42.1 g (0.1 mol) ofbis(2,4,6-trichlorophenyl)carbonate and 0.0122 g (10⁻⁴ mol) ofdimethylaminopyridine were stirred together at 180° C. in a nitrogenatmosphere for one hour. The temperature of the mixture was raised,while gradually lowering the pressure of the system. When the relativesolution viscosity reached 1.19, 0.025 g of tridecyl phosphite was addedto the reaction mixture, and the obtained mixture was further reactedlike in Example G-2 to give a polycarbonate.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior thereof are given in Table 7.

Comparative Example G-1

The polycarbonate prepared in Example G-1 was pelletized without beingblended with tridecyl phosphite and evaluated for the resistances toheat and hydrolysis. The results are given in Table 7.

Comparative Example G-2

Another polycarbonate was prepared in the same manner as that of ExampleG-2 except that a known catalyst for comparison, i.e., lithium hydroxideas an alkali metal hydroxide was used in an amount of 10⁻³ mole % basedon the 2,2-bis(4-hydroxyphenyl)propane used and that no tridecylphosphite was added.

Although the obtained polymer had an average molecular weight as high as26,500, the polymer was pale-yellow; the thermal decomposition thereofbegan at 375° C.; and the weight loss to reach 430° C. was 10%. Further,in the hydrolysis test at 90° C. and 100% RH, the retention of theaverage molecular weight after 30 days was as low as 65.3% and theresulting test sheet was translucent, had many white spots (partiallyincluding voids) all over and was brittle remarkably. These results aregiven in Table 7.

                                      TABLE 7                                     __________________________________________________________________________              Ex. G-1      Ex. G-2      Ex. G-3      Ex. G-4                      __________________________________________________________________________    Dihydroxy 2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-                                                     5                            compound  propane      propane      propane      propane (50 mole                                                              %)/2,2-                                                                       bis(4-hydroxy-3-t-butyl-                                                      2                                                                             phenyl)propane (50 mole                                                       %)                           Bisaryl carbonate                                                                       diphenyl carbonate                                                                         diphenyl carbonate                                                                         diphenyl carbonate                                                                         diphenyl carbonate           Catalyst  potassium borohydride                                                                      2-methylimidazole                                                                          dimethylamine-borane                                                                       4-dimethylaminopyridine                                          complex                                   Phosphite compound                                                                      tridecyl phosphite                                                                         "            "            "                                                   (rel. soln. viscosity at                                                      addn.: 1.18)                                           Hue of    nearly colorless                                                                           nearly colorless                                                                           nearly colorless                                                                           nearly colorless             polycondensate                                                                Av. mol. wt. of                                                                         24,300       26,800       23,300       25,000                       polycondensate                                                                Thermogravimetric                                                             analysis                                                                      T.sub.d   425° C.                                                                             428° C.                                                                             425° C.                                                                             428° C.               T.sub.5   458° C.                                                                             460° C.                                                                             458° C.                                                                             460° C.               T.sub.10  471° C.                                                                             475° C.                                                                             470° C.                                                                             473° C.               After hydrolysis for                                                          30 days at 90° C.                                                      and 100% RH                                                                   appearance                                                                              colorless and transparent                                                                  colorless and transparent                                                                  colorless and transparent                                                                  colorless and                                                                 transparent                  retention of mol. wt.                                                                   87.9%        88.0%        87.6%        90.2%                        __________________________________________________________________________                     Ex. G-5        Comp. Ex. G-1  Comp. Ex.                      __________________________________________________________________________                                                   G-2                            Dihydroxy compound                                                                             2,2-bis(4-hydoxyphenyl)-                                                                     2,2-bis(4-hydoxyphenyl)-                                                                     2,2-bis(4-hydoxyphenyl)-                        propane        propane        propane                        Bisaryl carbonate                                                                              bis(2,4,6-trichlorophenyl)                                                                   diphenyl carbonate                                                                           diphenyl carbonate                              carbonate                                                    Catalyst         dimethylaminopyridine                                                                        potassium borohydride                                                                        lithium hydroxide              Phosphite compound                                                                             tridecyl phosphite                                                                           --             --                                              (rel. soln. viscosity at                                                      addn: 1.19)                                                  Hue of polycondensate                                                                          nearly colorless                                                                             nearly colorless                                                                             pale-yellow                    Av. mol. wt. of  28,000         24,300         26,500                         polycondensate                                                                Thermogravimetric analysis                                                    T.sub.d          429° C. 380° C. 375° C.                 T.sub.5          462° C. 415° C. 414° C.                 T.sub.10         476° C. 435° C. 430° C.                 After hydrolysis for 30                                                       days at 90° C. and 100% RH                                             appearance       colorless and transparent                                                                    translucent    translucent                    retention of mol. wt.                                                                          88.9%          68.0%          65.3%                          __________________________________________________________________________

Example H-1

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane, potassiumborohydride (in an amount of 10⁻³ mole % based on the dihydroxy compoundfed) and 214 parts by weight of diphenyl carbonate were fed into areactor. The contents were stirred at 180° C. in a nitrogen atmospherefor one hour. The temperature of the contents was gradually raised to250° C., while the pressure of the system was lowered to 2 mmHg. Thetemperature of the contents was further raised and the contents werereacted at 280° C. in a vacuum of 0.5 mmHg for 2 hours to give apolycarbonate. This polycarbonate was nearly colorless and transparentand had an intrinsic viscosity [η] of 0.438 as determined in methylenechloride at 20° C. The average molecular weight Mv of the polycarbonatewas 24,300 as calculated according to the formula described in ExampleA-1.

254 g of the polycarbonate thus prepared was mixed with 0.254 g (0.1% byweight based on the polymer) of tris(4-nonylphenyl)phosphite on atumbling blender (mfd. by Matsui Seisakusho, SKB-50) and the obtainedmixture was extruded and pelletized by the use of a twin-screw extruder(HAAKE Buchler Product HBI System 90).

The pelletized composition was evaluated for the heat resistance asdescribed in Example A-1. The decomposition-initiating temperature,T_(d) was 430° C.; the temperature, T₅ was 466° C.; and the temperature,T₁₀ was 478° C.

Further, the above composition was also evaluated for the resistance tohydrolysis as described in Example A-1. After the lapse of 30 days underthe conditions of 90° C. and 100% RH (relative humidity), the retentionof the molecular weight was 86.2% based on the initial molecular weightand the resulting sheet was colorless and transparent and no abnormalphenomenon was observed in respect of the external appearance.

These results are given in Table 8.

Example H-2

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 0.164 g (2×10⁻²mol) of 2-methylimidazole and 21.4 g (0.1 mol) of diphenyl carbonatewere fed into a reactor. The contents were stirred at 180° C. in anitrogen atmosphere for one hour. The temperature of the contents wasgradually raised to 250° C., while the pressure of the system waslowered to 2 mmHg. At this point of time, 0.025 g (0.1% by weight basedon the whole polycondensate) of tris(4-nonylphenyl)phosphite was addedto the reactor. At the point of time of this addition, the relativesolution viscosity (polymer concentration: 0.5 g/100 ml, 20° C.,solvent: methylene chloride) presumed from the stirring torque was 1.17,while the one actually determined by the use of a sample of thepolycondensate was 1.18. The temperature of the contents was furtherraised and the contents were reacted at 280° C. in a vacuum of 0.5 mmHgfor 2 hours to give a polycarbonate. This polycarbonate was nearlycolorless and transparent and had an intrinsic viscosity [η] of 0.519 asdetermined in methylene chloride at 20° C. The average molecular weightMv of the polycarbonate was 27,000 as calculated according to theformula described in Example A-1.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior of the polycarbonate are given in Table8.

Example H-3

Another polycarbonate was prepared in the same manner as that of ExampleH-1 except that dimethylamine-borane complex (in an amount of 10⁻² mole% based on the dihydroxy compound fed) was used instead of potassiumborohydride. In a similar manner to that of Example H-1, a mixture ofthe polycarbonate thus obtained with tris(4-nonylphenyl)phosphite waspelletized and evaluated for the resistances to heat and hydrolysis. Theresults are given in Table 8.

Example H-4

114 parts by weight (50 mole %) of 2,2-bis(4-hydroxyphenyl)propane, 170parts by weight (50 mole %) of2,2-bis(4-hydroxy-3-t-butylphenyl)propane, 214 parts by weight ofdiphenyl carbonate and 4-dimethylaminopyridine (in an amount of 10⁻²mole % based on the dihydroxy compound fed) were fed into a reactor. Thecontents were reacted under the same conditions as those of Example H-1to give a copolycarbonate. In a similar manner to that of Example H-1, amixture of the copolycarbonate thus obtained withtris(4-nonylphenyl)phosphite was pelletized and evaluated for theresistances to heat and hydrolysis. The results are given in Table 8.

Example H-5

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 42.1 g (0.1 mol) ofbis(2,4,6-trichlorophenyl)carbonate and 0.0122 g (10⁻⁴ mol) ofdimethylaminopyridine were stirred together at 180° C. in a nitrogenatmosphere for one hour. The temperature of the mixture was raised,while gradually lowering the pressure of the system. When the relativesolution viscosity reached 1.19, 0.025 g of tris(4-nonylphenyl)phosphitewas added to the reaction mixture, and the obtained mixture was furtherreacted like in Example H-2 to give a polycarbonate.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior thereof are given in Table 8.

Comparative Example H-1

The polycarbonate prepared in Example H-1 was pelletized without beingblended with tris(4-nonylphenyl)phosphite and evaluated for theresistances to heat and hydrolysis. The results are given in Table 8.

Comparative Example H-2

Another polycarbonate was prepared in the same manner as that of ExampleH-2 except that a known catalyst for comparison, i.e., lithium hydroxideas an alkali metal hydroxide was used instead of 2-methylimidazole in anamount of 10⁻³ mole % based on 2,2-bis(4-hydroxyphenyl)propane used andthat no tris(4-nonylphenyl)phosphite was added.

Although the obtained polymer had an average molecular weight as high as26,500, the polymer was pale-yellow; the thermal decomposition thereofbegan at 375° C. and the weight loss to reach 430° C. was 10%. Further,in the hydrolysis test at 90° C. and 100% RH, the retention of theaverage molecular weight after 30 days was as low as 65.3% and theresulting test sheet was translucent, had many white spots (partiallyincluding voids) all over and was brittle remarkably. These results aregiven in Table 8.

                                      TABLE 8                                     __________________________________________________________________________              Ex. H-1      Ex. H-2      Ex. H-3      Ex. H-4                      __________________________________________________________________________    Dihydroxy 2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-                                                     3                            compound  propane      propane      propane      propane (50 mole                                                              %)/2,2-                                                                       bis(4-hydroxy-3-t-butyl-                                                      .                                                                             phenyl)propane (50 mole                                                       %)                           Bisaryl carbonate                                                                       diphenyl carbonate                                                                         diphenyl carbonate                                                                         diphenyl carbonate                                                                         diphenyl carbonate           Catalyst  potassium borohydride                                                                      2-methylimidazole                                                                          dimethylamine-borane                                                                       4-dimethylaminopyridine                                          complex                                   Phosphite compound                                                                      tris(4-nonylphenyl)                                                                        "            "            "                                      phosphite                                                                                  (rel. soln. viscosity at                                                      addn.: 1.18)                                           Hue of    nearly colorless                                                                           nearly colorless                                                                           nearly colorless                                                                           nearly colorless             polycondensate                                                                Av. mol. wt. of                                                                         24,300       27,000       23,300       25,000                       polycondensate                                                                Thermogravimetric                                                             analysis                                                                      T.sub.d   430° C.                                                                             432° C.                                                                             430° C.                                                                             430° C.               T.sub.5   466° C.                                                                             470° C.                                                                             465° C.                                                                             469° C.               T.sub.10  478° C.                                                                             486° C.                                                                             477° C.                                                                             482° C.               After hydrolysis for                                                          30 days at 90° C.                                                      and 100% RH                                                                   appearance                                                                              colorless and transparent                                                                  colorless and transparent                                                                  colorless and transparent                                                                  colorless and                                                                 transparent                  retention of mol. wt.                                                                   86.2%        87.8%        87.0%        88.0%                        __________________________________________________________________________                     Ex. H-5        Comp. Ex. H-1  Comp. Ex.                      __________________________________________________________________________                                                   H-2                            Dihydroxy compound                                                                             2,2-bis(4-hydroxyphenyl)-                                                                    2,2-bis(4-hydroxyphenyl)-                                                                    2,2-bis(4-hydroxyphenyl)-                       propane        propane        propane                        Bisaryl carbonate                                                                              bis(2,4,6-trichlorophenyl)                                                                   diphenyl carbonate                                                                           diphenyl carbonate                              carbonate                                                    Catalyst         dimethylaminopyridine                                                                        potassium borohydride                                                                        lithium hydroxide              Phosphite compound                                                                             tris(4-nonylphenyl)                                                                          --             --                                              phosphite                                                                     (rel. soln. viscosity at                                                      addn: 1.19)                                                  Hue of polycondensate                                                                          nearly colorless                                                                             nearly colorless                                                                             pale-yellow                    Av. mol. wt. of  26,800         24,300         26.500                         polycondensate                                                                Thermogravimetric analysis                                                    T.sub.d          432° C. 380° C. 375° C.                 T.sub.5          470° C. 415° C. 414° C.                 T.sub.10         486° C. 435° C. 430° C.                 After hydrolysis for 30                                                       days at 90° C. and 100% RH                                             appearance       colorless and transparent                                                                    translucent    translucent                    retention of mol. wt.                                                                          88.0%          68.0%          65.3%                          __________________________________________________________________________

Example I-1

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane, potassiumborohydride (in an amount of 10⁻³ mole % based on the dihydroxy compoundfed) and 214 parts by weight of diphenyl carbonate were fed into areactor. The contents were stirred at 180° C. in a nitrogen atmospherefor one hour. The temperature of the contents was gradually raised to250° C., while the pressure of the system was lowered to 2 mmHg. Thetemperature of the contents was further raised and the contents werereacted at 280° C. in a vacuum of 0.5 mmHg for 2 hours to give apolycarbonate. This polycarbonate was nearly colorless and transparentand had an intrinsic viscosity [η] of 0.438 as determined in methylenechloride at 20° C. The average molecular weight Mv of the polycarbonatewas 24,300 as calculated according to the formula described in ExampleA-1.

254 g of the polycarbonate thus obtained was mixed with 0.254 g (0.1% byweight based on the polymer) of tridecyl phosphite and 0.254 g ofoctadecyl 3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate on a tumblingblender (mfd. by Matsui Seisakusho, SKB-50) and the obtained mixture wasextruded and pelletized by the use of a twin-screw extruder (HAAKEBuchler Product HBI System 90).

The pelletized composition was evaluated for the heat resistance asdescribed in Example A-1. The decomposition-initiating temperature,T_(d) was 429° C.; the temperature, T₅ was 463° C.; and the temperature,T₁₀ was 470° C.

Further, the polycarbonate composition was also evaluated for theresistance to hydrolysis as described in Example A-1. After the lapse of30 days under the conditions of 90° C. and 1004% RH (relative humidity),the retention of the molecular weight was 86.7% based on the initialmolecular weight and the resulting sheet was colorless and transparentand no abnormal phenomenon was observed in respect of the externalappearance.

These results are given in Table 9.

Example I-2

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 0.164 g (2×10⁻²mol) of 2-methylimidazole and 21.4 g (0.1 mol) of diphenyl carbonatewere fed into a reactor. The contents were stirred at 180° C. in anitrogen atmosphere for one hour. The temperature of the contents wasgradually raised to 250° C., while the pressure of the system waslowered to 2 mmHg. At this point of time, tridecyl phosphite andoctadecyl 3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate were addedinto the reactor each in an amount of 0.025 g (0.1% by weight based onthe whole polycondensate). At the point of time of this addition, therelative solution viscosity (polymer concentration: 0.5 g/100 ml, 20°C., solvent: methylene chloride) presumed from the stirring torque was1.17, while the one actually determined by the use of a sample of thepolycondensate was 1.18. The temperature of the contents was furtherraised and the contents were reacted at 280° C. in a vacuum of 0.5 mmHgfor 2 hours to give a polycarbonate. This polycarbonate was nearlycolorless and transparent and had an intrinsic viscosity [η] of 0.478 asdetermined in methylene chloride at 20° C. The average molecular weightMv of the polycarbonate was 27,000 as calculated according to theformula described in Example A-1.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior of the obtained polymer are given inthe Table 9.

Example I-3

Another polycarbonate was prepared in a similar manner to that ofExample I-1 except that dimethylamine-borane complex (in an amount of10⁻² mole % based on the dihydroxy compound fed) was added instead ofpotassium borohydride. In a similar manner to that of Example I-1, amixture of the obtained polycarbonate with tridecyl phosphite andoctadecyl 3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate waspelletized and evaluated for the resistances to heat and hydrolysis. Theresults are given in Table 9.

Example 1-4

114 parts by weight (50 mole %) of 2,2-bis(4-hydroxyphenyl)propane, 170parts by weight (50 mole of 2,2-bis(4-hydroxy-3-t-butylphenyl)propane,214 parts by weight of diphenyl carbonate and 4-dimethylaminopyridine(in an amount of 10⁻² mole % based on the dihydroxy compound fed) werereacted under the same conditions as those of Example I-1 to give acopolycarbonate. In a similar manner to that Example I-1, a mixture ofthe obtained copolycarbonate with tridecyl phosphite and octadecyl3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate was pelletized andevaluated for the resistances to neat and hydrolysis. The results aregiven in the Table 9.

Example I-5

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 42.1 g (0.1 mol) ofbis(2,4,6-trichlorophenyl)carbonate and 0.0122 g (10⁻⁴ mol) ofdimethylaminopyridine were stirred together in a nitrogen atmosphere at180° C. for one hour. Thereafter the temperature of the mixture wasgradually raised while lowering the pressure of the system. When therelative solution viscosity reached 1.19, tridecyl phosphite andoctadecyl 3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate were added tothe reaction mixture each in an amount of 0.025 g, and the obtainedmixture was further reacted like in Example I-2.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior of the obtained polymer are given inthe Table 9.

Comparative Example I-1

The polycarbonate prepared in Example I-1 was pelletized without beingblended with tridecyl phosphite or octadecyl 3-(4',5'-di-t-butyl-4'-hydroxyphenyl)propionate, and evaluated for theresistances to heat and hydrolysis. The results are given in Table 9.

Comparative Example I-2

Another polycarbonate was prepared in the same manner as that of ExampleI-2 except That a known catalyst for comparison, i.e., lithium hydroxideas an alkali metal hydroxide was used instead of 2-methylimidazole in anamount of 10⁻³ mole % based on the 2,2-bis(4-hydroxyphenyl)propane andthat neither tridecyl phosphite nor octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate was added.

Although the obtained polymer had an average molecular weight as high as26,500, the polymer was pale-yellow; the thermal decomposition thereofbegan at 375° C. and the weight loss to reach 430° C. was 10%. Further,in the hydrolysis test at 90° C. and the retention of the averagemolecular weight after 30 days was as low as 65.3% and the resultingtest sheet was translucent, had many small white spots (partiallyincluding voids) all over and was brittle remarkably. These results aregiven in Table 9.

                                      TABLE 9                                     __________________________________________________________________________              Ex. I-1      Ex. I-2      Ex. I-3      Ex. I-4                      __________________________________________________________________________    Dihydroxy 2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-    compound  propane      propane      propane      propane (50 mole %)                                                           2,2-bis(4-hydroxy-3-t-                                                        butylphenyl)propane(50                                                        mole %)                      Bisaryl carbonate                                                                       diphenyl carbonate                                                                         diphenyl carbonate                                                                         diphenyl carbonate                                                                         diphenyl carbonate           Catalyst  potassium borohydride                                                                      2-methylimidazole                                                                          dimethylamineborane                                                                        4-dimethylaminopyridine                                          complex                                   Phosphite compound                                                                      tridecyl phosphite                                                                         "            "            "                            Hindered phenol                                                                         octadecyl 3-(3',5'-di-t-                                                                   "            "            "                            compound  butyl-4'-hydroxyphenyl)-                                                      propionate                                                                                 (rel. soln. viscosity at                                                      addn.: 1.18)                                           Hue of    nearly colorless                                                                           nearly colorless                                                                           nearly colorless                                                                           nearly colorless             polycondensate                                                                Av. mol. wt. of                                                                         24,300       27,000       23,300       25,000                       polycondensate                                                                Thermogravimetric                                                             analysis                                                                      T.sub.d   429° C.                                                                             430° C.                                                                             429° C.                                                                             430° C.               T.sub.5   463° C.                                                                             468° C.                                                                             463° C.                                                                             468° C.               T.sub.10  470° C.                                                                             482° C.                                                                             470° C.                                                                             482° C.               After hydrolysis for                                                          30 days at 90° C.                                                      and 100% RH                                                                   appearance                                                                              colorless and transparent                                                                  colorless and transparent                                                                  colorless and transparent                                                                  colorless and                                                                 transparent                  retention of mol. wt.                                                                   86.7%        87.6%        87.0%        90.2%                        __________________________________________________________________________                     Ex. I-5        Comp. Ex. I-1  Comp. Ex.                      __________________________________________________________________________                                                   I-2                            Dihydroxy compound                                                                             2,2-bis(4-hydroxyphenyl)-                                                                    2,2-bis(4-hydroxyphenyl)-                                                                    2,2-bis(4-hydroxyphenyl)-                       propane        propane        propane                        Bisaryl carbonate                                                                              bis(2,4,6-trichlorophenyl)                                                                   diphenyl carbonate                                                                           diphenyl carbonate                              carbonate                                                    Catalyst         dimethylaminopyridine                                                                        potassium borohydride                                                                        lithium hydroxide              Phosphite compound                                                                             tridecyl phosphite                                                                           --             --                             Hindered phenol compound                                                                       octodecyl 3-(3',5'-di-t-                                                                     --             --                                              butyl-4'-hydroxyphenyl)-                                                      propionate                                                                    (rel. soln. viscosity at                                                      addn: 1.19)                                                  Hue of polycondensate                                                                          nearly colorless                                                                             nearly colorless                                                                             pale-yellow                    Av. mol. wt. of  28,000         24,300         26,500                         polycondensate                                                                Thermogravimetric analysis                                                    T.sub.d          432° C. 380° C. 375° C.                 T.sub.5          468° C. 415° C. 414° C.                 T.sub.10         482° C. 435° C. 430° C.                 After hydrolysis for 30                                                       days at 90° C. and 100% RH                                             appearance       colorless and transparent                                                                    translucent    translucent                    retention of mol. wt.                                                                          87.8%          68.0%          65.3%                          __________________________________________________________________________

Example J-1

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane, potassiumborohydride (in an amount of 10⁻³ mole % based on the dihydroxy compoundfed) and 214 parts by weight of diphenyl carbonate were fed into areactor. The contents were stirred at 180° C. in a nitrogen atmospherefor one hour. The temperature of the contents was gradually raised to250° C., while the pressure of the system was lowered to 2 mmHg. Thetemperature of the contents was further raised and the contents werereacted at 280° C. in a vacuum of 0.5 mmHg for 2 hours to give apolycarbonate. This polycarbonate was nearly colorless and transparentand had an intrinsic viscosity [η] of 0.438 as determined in methylenechloride at 20° C. The average molecular weight Mv of the polycarbonatewas 24,300 as calculated according to the formula described in ExampleA-1.

254 g of the polycarbonate thus obtained was mixed with 0.254 g (0.1% byweight based on the polymer) oftetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite on atumbling blender (mfd. by Matsui Seisakusho, SKB-50) and the obtainedmixture was extruded and pelletized by the use of a twin-screw extruder(HAAKE Buchler Product HBI System 90). The pelletized composition wasevaluated for the heat resistance as described in Example A-1. Thedecomposition-initiating temperature, T_(d) was 430° C.; thetemperature, T₅ was 465° C.; and the temperature, T₁₀ was 478° C.

Further, the polycarbonate composition was also evaluated for theresistance to hydrolysis as described in Example A-1. After rue lapse of30 days under the conditions of 90° C. and 100% RH (relative humidity),the retention of the molecular weight was 87.1% based on the initialmolecular weight and the resulting sheet was colorless and transparentand no abnormal phenomenon was observed in respect of the externalappearance.

These results are given in Table 10.

Example J-2

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 0.164 g (2×10⁻²mol) of 2-methylimidazole and 21.4 g (0.1 mol) of diphenyl carbonatewere fed into a reactor. The contents were stirred at 180° C. in anitrogen atmosphere for one hour. The temperature of the contents wasgradually raised to 250° C., while the pressure of the system waslowered to 2 mmHg. At this point of time, 0.025 g (0.1% by weight of thewhole polycondensate) of tetrakis(2,4-di-t-butyl)-4,4'-biphenylenediphosphonite was added to the reactor. At the point oftime of this addition, the relative solution viscosity (polymerconcentration: 0.5 g/100 ml, 20° C., solvent: methylene chloride)presumed from the stirring torque was 1.17, while the one actuallydetermined by the use of a sample of the polycondensate was 1.18. Thetemperature of the contents was further raised and the contents werereacted at 280° C. in a vacuum of 0.5 mmHg for 2 hours to give apolycarbonate. This polycarbonate was nearly colorless and transparentand had an intrinsic viscosity [η] of 0.492 as determined in methylenechloride at 20° C. The average molecular weight Mv of the polycarbonatewas 28,000 as calculated according to the formula described in ExampleA-1.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior of the obtained polymer are given inthe Table 10.

Example J-3

Another polycarbonate was prepared in a similar manner to that of theExample J-1 except that dimethylamine-borane complex (in an amount of10⁻² mole based on the dihydroxy compound fed) was added instead ofpotassium borohydride. In a similar manner to that of the Example J-1, amixture of the obtained polycarbonate withtetrakis(2,4-di-t-butyl)-4,4'-biphenylenediphosphonite was pelletizedand evaluated for the resistances to heat and hydrolysis. The resultsare given in Table 10.

Example J-4

114 parts by weight (50 mole %) of 2,2-bis(4-hydroxyphenyl)propane, 170parts by weight (50 mole %) of2,2-bis(4-hydroxy-3-t-butylphenyl)propane, 214 parts by weight ofdiphenyl carbonate and 4-dimethylaminopyridine (in an amount of 10⁻²mole % based on the dihydroxy compound fed) were fed into a reactor. Thecontents were reacted under the same conditions as those of Example J-1to give a copolycarbonate. In a similar manner to that of Example J-1, amixture of the obtained copolycarbonate withtetrakis(2,4-di-t-butyl)-4,4'-biphenylenediphosphonite was pelletizedand evaluated for the resistances to heat and hydrolysis. The resultsare given in Table 10.

Example J-5

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 42.1 g (0.1 mol) ofbis(2,4,6-trichlorophenyl)carbonate and 0.0122 g (10⁻⁴ mol) ofdimethylaminopyridine were stirred together in a nitrogen atmosphere at180° C. for one hour. Thereafter, the temperature of the mixture wasgradually raised while lowering The pressure of she system. When therelative solution viscosity reached 1.19, 0.025 g oftetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite was addedto the reaction mixture, and the obtained mixture was further reactedlike in Example J-2.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior of the obtained polymer are given inthe Table 10.

Comparative Example J-1

The polycarbonate prepared in Example J-1 was pelletized without beingblended withtetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite, andevaluated for the resistances to heat and hydrolysis. The results aregiven in Table 10.

Comparative Example J-2

Another polycarbonate was prepared in the same manner as that of ExampleJ-2 except that a known catalyst for comparison, i.e., lithium hydroxideas an alkali metal hydroxide was used instead of 2-methylimidazole in anamount of 10⁻³ mole % based on the 2,2-bis(4-hydroxyphenyl)propane andthat no tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite wasadded.

Although the obtained polymer had an average molecular weight as high as26,500, the polymer was pale-yellow; the thermal decomposition thereofbegan at 375° C. and the weight loss to reach 430° C. was 10%. Further,in the hydrolysis test at 90° C. and 100% RH, the retention of theaverage molecular weight after 30 days was as low as 65.3% and theresulting test sheet was translucent, had many small white spots(partially including voids) all over and was brittle remarkably. Theseresults are given in the Table 10.

                                      TABLE 10                                    __________________________________________________________________________              Ex. J-1      Ex. J-2      Ex. J-3      Ex. J-4                      __________________________________________________________________________    Dihydroxy 2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-    compound  propane      propane      propane      propane (50 mole                                                              %)/2,2-                                                                       bis(4-hydroxy-3-t-butyl-                                                      phenyl)propane (50 mole                                                       %)                           Bisaryl carbonate                                                                       diphenyl carbonate                                                                         diphenyl carbonate                                                                         diphenyl carbonate                                                                         diphenyl carbonate           Catalyst  potassium borohydride                                                                      2-methylimidazole                                                                          dimethylamine-borane                                                                       4-dimethylaminopyridine                                          complex                                   Phosphonite                                                                             tetrakis(2,4-di-t-                                                                         "            "            "                            compound  butylphenyl)-4,4'-                                                            biphenylenediphosphonite                                                                   (rel. soln. viscosity at                                                      addn.: 1.18)                                           Hue of    nearly colorless                                                                           nearly colorless                                                                           nearly colorless                                                                           nearly colorless             polycondensate                                                                Av. mol. wt. of                                                                         24,300       28,000       23,300       25,000                       polycondensate                                                                Thermogravimetric                                                             analysis                                                                      T.sub.d   430° C.                                                                             432° C.                                                                             430° C.                                                                             430° C.               T.sub.5   465° C.                                                                             470° C.                                                                             467° C.                                                                             469° C.               T.sub.10  478° C.                                                                             486° C.                                                                             481° C.                                                                             482° C.               After hydrolysis for                                                          30 days at 90° C.                                                      and 100% RH                                                                   appearance                                                                              colorless and transparent                                                                  colorless and transparent                                                                  colorless and transparent                                                                  colorless and                                                                 transparent                  retention of mol. wt.                                                                   87.1%        88.7%        88.0%        91.3%                        __________________________________________________________________________                     Ex. J-5        Comp. Ex. J-1  Comp. Ex.                      __________________________________________________________________________                                                   J-2                            Dihydroxy compound                                                                             2,2-bis(4-hydroxyphenyl)-                                                                    2,2-bis(4-hydroxyphenyl)-                                                                    2,2-bis(4-hydroxyphenyl)-                       propane        propane        propane                        Bisaryl carbonate                                                                              bis(2,4,6-trichlorophenyl)                                                                   diphenyl carbonate                                                                           diphenyl carbonate                              carbonate                                                    Catalyst         dimethylaminopyridine                                                                        potassium borohydride                                                                        lithium hydroxide              Phosphonite compound                                                                           tetrakis(2,4-di-t-butyl-                                                                     --             --                                              phenyl)-4,4'-biphenylene-                                                     diphosphonite                                                                 (rel. soln. viscosity at                                                      addn: 1.19)                                                  Hue of polycondensate                                                                          nearly colorless                                                                             nearly colorless                                                                             pale-yellow                    Av. mol. wt. of  28,000         24,300         26,500                         polycondensate                                                                Thermogravimetric analysis                                                    T.sub.d          432° C. 380° C. 375° C.                 T.sub.5          470° C. 415° C. 414° C.                 T.sub.10         486° C. 435° C. 430° C.                 After hydrolysis for 30                                                       days at 90° C. and 100% RH                                             appearance       colorless and transparent                                                                    translucent    translucent                    retention of mol. wt.                                                                          88.9%          68.0%          65.3%                          __________________________________________________________________________

Example K-1

4,560 g (20 mol) of 2,2-bis(4-hydroxyphenyl)propane, 489 mg (4×10⁻³ mol)of 4-dimethylaminopyridine, 0.49 mg (5×10⁻⁶ mol) of potassium acetate,4391.5 g (20.5 mol) of diphenyl carbonate and 1824 g (400 ppm based on2,2-bis(4-hydroxyphenyl)propane) of tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphite were fed in a tank reactor made ofHastelloy C-276 and stirred at 160° C. for one hour in nitrogen. Thenthe temperature was gradually elevated to 260° C. while the pressure wasgradually reduced to 0.1Torr and polycondensation was conducted underthese conditions for 4 hours while distilling off phenol formed. Then,the reaction was conducted in a tank-type twin-screw self-cleaningreactor for 50 min. Thus, a colorless, transparent polycarbonate wasobtained.

The average molecular weight Mv of the polycarbonate was 28,600 ascalculated according to the formula described in Example A-1(determination of the intrinsic viscosity [η] was conducted withUbbelohde's viscometer).

The terminal hydroxyl content determined by ¹⁴ C-NMR was 30 molar %.

Example K-2

Stirring was conducted in nitrogen for one hour under the sameconditions as those of Example K-1 except that 4-dimethylaminopyridinewas replaced with 7.6 mg (1×10⁻⁴ mol) of tetramethylammonium hydroxide,and that potassium acetate was replaced with 0.33 mg (5×10⁻⁶ mol) oflithium acetate, and then polycondensation was conducted in the samemanner as that of Example K-1 to obtain a colorless, transparentpolycarbonate. The viscosity-average molecular weight (Mv) of theproduct was determined to be 27,800. The terminal hydroxyl content was28 molar %.

Example K-3

2280 g (10 mol, 50 molar %) of 2,2-bis(4-hydroxyphenyl)propane, 3400 g(10 mol, 50 molar %) of 2,2-bis(4-hydroxy-3-tert-butylphenyl)propane,4434 g (20.7 mol) of diphenyl carbonate, 0.0122 g (1×10⁻⁴ mol) of4-dimethylaminopyridine and 0.49 mg (5×10⁻⁶ mol) of potassium acetatewere stirred together in nitrogen for one hour and then polycondensationwas conducted in the same manner as that of Example K-1 to obtain acolorless, transparent polycarbonate. The viscosity-average molecularweight (Mv) of the product was 24,500. The terminal hydroxyl content was18 molar %.

Example K-4

The polycondensation reaction was conducted in the same manner as thatof Example K-1 except that 4-dimethylaminopyridine and potassium acetatewere replaced with 7.6 mg (1×10⁻⁴ mol) of tetramethylammonium hydroxideto obtain a colorless, transparent polycarbonate. The viscosity-averagemolecular weight (Mv) of the product was determined to be 18,000. Theterminal hydroxyl content was 50 molar %.

Example K-5

The polycondensation reaction was conducted in the same manner as thatof Example K-1 except that 4-dimethylaminopyridine and potassium acetatewere replaced with 245 mg (2×10⁻³ mol) of 4-dimethylaminopyridine aloneto obtain a colorless, transparent polycarbonate. The viscosity-averagemolecular weight (Mv) of the product was determined to be 23,000. Theterminal hydroxyl content was 42 molar %.

Example K-6

30 mg of octadecyl 3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate wasadded to 100 g of the polycarbonate obtained in Example K-1 and themixture was kneaded and extruded on a twin-screw extruder to obtain apolycarbonate composition.

Comparative Example K-1

The reaction was conducted in the same manner as that of Example K-1except that no tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylenediphosphite was used to obtain a colorless, transparent polycarbonatehaving a viscosity-average molecular weight (Mv) of 30,000 and aterminal hydroxyl content of 35 molar %. Sheets having a thickness of0.5 mm and a size of 50 mm×50 mm were prepared from the polycarbonate orpolycarbonate composition obtained in Examples K-1 to K-6 or ComparativeExample K-1 by the hot press/ quenching method. After leaving them tostand at 160° C. for 10 days, the viscosity-average molecular weightthereof was determined. Further the cleavage ratio was determinedaccording to the formula given below: ##EQU1## wherein Mv₀ representsthe viscosity-average molecular weight at the initiation of heating andMv₁₀ represents the viscosity-average molecular weight after 10 days.

The results are given in Table 11.

                  TABLE 11                                                        ______________________________________                                                  Visc.-av. mol. wt. of                                                         pressed sheet                                                               before     after 10 cleavage                                                  initiation days     ratio                                             ______________________________________                                        Ex. K-1   28,600       25,900   0.10                                          Ex. K-2   27,800       25,600   0.09                                          Ex. K-3   24,500       23,000   0.07                                          Ex. K-4   18,000       16,800   0.07                                          Ex. K-5   23,000       21,500   0.07                                          Ex. K-6   28,300       26,000   0.09                                          Comp. Ex. 30,000       19,000   0.57                                          K-1                                                                           ______________________________________                                    

Example L-1

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane, potassiumborohydride (in an amount of 10⁻³ mole % based on the dihydroxy compoundfed) and 214 parts by weight of diphenyl carbonate were fed into areactor. The contents were stirred at 180° C. in a nitrogen atmospherefor one hour. The temperature of the contents was gradually raised to250° C., while the pressure of the system was lowered to 2 mmHg. Thetemperature of the contents was further raised and the contents werereacted at 280° C. in a vacuum of 0.5 mmHg for 2 hours to give apolycarbonate. This polycarbonate was nearly colorless and transparentand had an intrinsic viscosity [η] of 0.519 as determined in methylenechloride at 20° C. The average molecular weight Mv of the polycarbonatewas 29,900 as calculated according to the formula described in ExampleA-1.

254 g of the polycarbonate thus obtained was mixed with 0.254 g (0.1% byweight based on the polymer) oftetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite and 0.254 g(0.14 by weight based on the polymer) of octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate on a tumbling blender (mfd. byMatsui Seisakusho, SKB-50) and the obtained mixture was extruded andpelletized by the use of a twin-screw extruder (HAAKE Buchler ProductHBI System 90).

The pelletized composition was evaluated for the heat resistance asdescribed in Example A-1. The decomposition-initiating temperature,T_(d) was 433° C.; the temperature, T₅ was 472° C.; and the temperature,T₁₀ was 488° C.

Further, the polycarbonate composition was also evaluated for theresistance to hydrolysis as described in Example A-1. After the lapse of30 days under the conditions of 90° C. and 100% RH (relative humidity),the retention of the molecular weight was 89.8% based on the initialmolecular weight and the resulting sheet was colorless and transparentand no abnormal phenomenon was observed in respect of the externalappearance.

These results are given in Table 12.

Example L-2

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane was dissolved ina 0.1N aqueous solution of sodium hydroxide, followed by the addition of214 parts by weight of diphenyl carbonate and dichloromethane. Gaseousphosgene was blown into the obtained mixture, while vigorously stirringthe mixture. The obtained viscous solution was separated and thedichloromethane solution was distilled to remove the dichloromethane,giving a nearly colorless polycarbonate. This polycarbonate was washedwith methanol several times, dried and examined for theviscosity-average molecular weight (Mv) in a similar manner to that ofExample L-1. The average molecular weight (Mv) thereof was 28,000.

The polycarbonate composition containingtetrakis-[methylene-(3,5-di-t-butyl-4-hydroxyhydrocinnamate)]-methaneinstead of octadecyl 3-(3', 5'-t-butyl-4'-hydroxyphenyl)propionate waspelletized in a similar manner to that of Example L-1. The pelletizedcomposition thus obtained was evaluated for the resistances to heat andhydrolysis in a similar manner to that of Example L-1. The results aregiven in the Table 12.

Example L-3

Another polycarbonate was prepared in a similar manner to that ofExample L-1 except that 4-dimethylaminopyridine (in an amount of 10⁻²mole % based on the dihydroxy compound fed) was added instead ofpotassium borohydride. In a similar manner to that of Example L-1, amixture of the obtained polycarbonate with octadecyl 3-(3',5'-t-butyl-4'-hydroxyphenyl)propionate was pelletized and evaluated forthe resistances to heat and hydrolysis. The results are given in theTable 12.

Example L-4

114 parts by weight (50 mole %) of 2,2-bis(4-hydroxyphenyl)propane, 170pares by weight (50 mole %) of 2,2-bis(4-hydroxy-3-t-butylphenyl)propaneand imidazole (in an amount of 10⁻² mole % based on the dihydroxycompound) were fed into a reactor. The contents were reacted under thesame conditions as those of Example L-1 to give a copolycarbonate. In asimilar manner to that of Example L-1, a mixture of the obtainedcopolycarbonate with octadecyl 3-(3',5'-t-butyl-4'-hydroxyphenyl)propionate was pelletized and evaluated forthe resistances to heat and hydrolysis. The results are given in Table12.

Comparative Example L-1

The polycarbonate prepared in Example L-1 was pelletized without beingblended withtetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite oroctadecyl 3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate, andevaluated for the resistances to heat and hydrolysis. The results aregiven in Table 12.

                                      TABLE 12                                    __________________________________________________________________________              Ex. L-1    Ex. L-2    Ex. L-3    Ex. L-4   Comp. Ex.                __________________________________________________________________________                                                         L-1                      Dihydroxy 2,2-bis(4-hydroxy-                                                                       2,2-bis(4-hydroxy-                                                                       2,2-bis(4-hydroxy-                                                                       2,2-bis(4-hydroxy-                                                                      2,2-bis(4-hydroxy)-      compound  phenyl)propane: 254 g                                                                    phenyl)propane: 254 g                                                                    phenyl)propane: 254 g                                                                    phenyl)propane                                                                          phenyl)propane:                                                     mole %)/2,2-bis(4-                                                                      254 g                                                               hydroxy-3-t-butyl-                                                            phenyl)propane (50                                                            mole %): 282 g                     Tetrakis(2,4-di-t-                                                                      0.254 g    0.254 g    0.254 g    0.282 g   --                       butyl-phenyl)-4,4'-                                                                     (0.1 wt %) (0.1 wt %) (0.1 wt %) (0.1 wt %)                         biphenylene-                                                                  diphosphonite                                                                 Octadecyl 3-(3',5'-                                                                     0.254 g    --         0.254 g    0.282 g   --                       di-t-butyl-4'-                                                                          (0.1 wt %)            (0.1 wt %) (0.1 wt %)                         hydroxyphenyl)-                                                               propionate                                                                    Tetrakis[methyl-                                                                        --         0.254 g    --         --        --                       ene(3,5-di-t-butyl-4-                                                                              (0.1 wt %)                                               hydroxy-hydrocinna-                                                           mate)]methane                                                                 Hue of    nearly colorless                                                                         nearly colorless                                                                         nearly colorless                                                                         colorless nearly colorless         polycondensate                                                                Av. mol. wt. of                                                                         29,900     28,000     28,200     25,200    29,900                   polycondensate                                                                Thermogravimetric                                                             analysis                                                                      T.sub.d   433° C.                                                                           432° C.                                                                           433° C.                                                                           420° C.                                                                          375° C.           T.sub.5   472° C.                                                                           472° C.                                                                           472° C.                                                                           464° C.                                                                          414° C.           T.sub.10  488° C.                                                                           490° C.                                                                           491° C.                                                                           480° C.                                                                          430° C.           After hydrolysis for                                                          30 days at 90° C.                                                      and 100% RH                                                                   appearance                                                                              colorless and                                                                            colorless and                                                                            colorless and                                                                            colorless and                                                                           transparent                        transparent                                                                              transparent                                                                              transparent                                                                              transparent                        retension of mol. wt.                                                                   89.8%      89.5%      89.6%      90.2%     67.3%                    __________________________________________________________________________

Example M-1

228 parts by weight of 2,2-bis(4-hydroxyphenyl)propane, potassiumborohydride (in an amount of 10⁻³ mole % based on the dihydroxy compoundfed) and 214 parts by weight of diphenyl carbonate were fed into areactor. The contents were stirred at 180° C. in a nitrogen atmospherefor one hour. The temperature of the contents was gradually raised to250° C., while the pressure of the system was lowered to 2 mmHg. Thetemperature of the contents was further raised and the contents werereacted at 280° C. in a vacuum of 0.5 mmHg for 2 hours to give apolycarbonate. This polycarbonate was nearly colorless and transparentand had an intrinsic viscosity [η] of 0.438 as determined in methylenechloride at 20° C. The average molecular weight Mv of the polycarbonatewas 24,300 as calculated according to the formula described in ExampleA-1.

254 g of the polycarbonate thus obtained was mixed with 0.127 g oftris(4-nonylphenyl)phosphite, 0.127 g oftris(2,4-di-t-butylphenyl)phosphite and 0.254 g of octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate on a tumbling blender (mfd. byMatsui Seisakusho, SKB-50) and the obtained mixture was extruded andpelletized by the use of a twin-screw extruder (HAAKE Buchler ProductHBI System 90). The pelletized composition was evaluated for the heatresistance as described in Example A-1. The decomposition-initiatingtemperature, T_(d) was 430° C.: the temperature, T₅ was 470° C.; and thetemperature, T₁₀ was 485° C.

Further, the polycarbonate composition was also evaluated for theresistance to hydrolysis as described in Example A-1. After the lapse of30 days under the conditions of 90° C. and 100% RH (relative humidity),the retention of the molecular weight was 89.04% based on the initialmolecular weight and the resulting sheet was colorless and transparentand no abnormal phenomenon was observed in respect of the externalappearance.

These results are given in Table 13.

Example M-2

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 0.164 g (2×10⁻²mol) of 2-methylimidazole and 21.4 g (0.1 mol) of diphenyl carbonatewere fed into a reactor. The contents were stirred at 180° C. in anitrogen atmosphere for one hour. The temperature of the contents wasgradually raised to 250° C., while the pressure of the system waslowered to 2 mmHg. At this point of time, 0.0125 g oftris(4-nonylphenyl)phosphite, 0.0125 g oftetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite and 0.025 gof octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate were addedto the reactor. At the point of time of this addition, the relativesolution viscosity (polymer concentration: 0.5 g/100 ml, 20° C.,solvent: methylene chloride) presumed from the stirring torque was 1.17,while the one actually determined by the use of a sample of thepolycondensate was 1.18. The temperature of the contents was furtherraised and the contents were reacted at 280° C. in a vacuum of 0.5 mmHgfor 2 hours to give a polycarbonate. This polycarbonate was nearlycolorless and transparent and had an intrinsic viscosity [η] of 0.519 asdetermined in methylene chloride at 20° C. The average molecular weightM of the polycarbonate was 29,900 as calculated according to the formuladescribed in Example A-1.

The hue, viscosity-average molecular weight, thermal decompositionbehavior and hydrolysis behavior of the polymer are given in Table 13.

Example M-3

Another polycarbonate was prepared in a similar manner to that ofExample M-1 except that dimethylamine-borane complex (in an amount of10⁻² mole % based on the dihydroxy compound fed) was added instead ofpotassium borohydride. The polycarbonate thus obtained was mixed with0.084 g of tridecyl phosphite, 0.084 g ofbis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite. 0,084 gof tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite and0.254 g of octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate. Ina similar manner to that of Example M-1, the obtained mixture waspelletized and evaluated for the resistances to heat and hydrolysis. Theresults are given in Table 13.

Example M-4

114 parts by weight (50 mole %) of 2,2-bis(4-hydroxyphenyl)propane, 170parts by weight (50 mole %) of2,2-bis(4-hydroxy-3-t-butylphenyl)propane, 214 parts by weight ofdiphenyl carbonate and 4-dimethylaminopyridine (in an amount of 10⁻²mole % based on the dihydroxy compound) were fed into a reactor. Thecontents were reacted under the same conditions as those of Example M-1to give a copolycarbonate. This copolycarbonate was mixed with 0.127 gof tris(4-nonylphenyl)phosphite, 0.127 g oftetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite and 0.254 gof octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate. In asimilar manner to that of Example M-1, the obtained composition waspelletized and evaluated for the resistances to heat and hydrolysis. Theresults are given in Table 13.

Example M-5

22.8 g (0.1 mol) of 2,2-bis(4-hydroxyphenyl)propane, 42.1 g (0.1 mol) ofbis(2,4,6-trichlorophenyl)carbonate and 0.0122 g (10⁻⁴ mol) ofdimethylaminopyridine were stirred together in a nitrogen atmosphere at180° C. for one hour. The temperature of the resulting mixture wasgradually raised while lowering the pressure of the system. When therelative solution viscosity reached 1.19, 0.0125 g oftris(4-nonylphenyl)phosphite, 0.0125 g oftris(2,4-di-t-butylphenyl)phosphite and 0.025 g of octadecyl3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate were added to thereaction mixture and The obtained mixture was further reacted like inExample M-2 to give a polymer.

The hue, viscosity-average molecular weight, Thermal decompositionbehavior and hydrolysis behavior of the polymer are given in the Table13.

Comparative Example M-1

The polycarbonate prepared in Example M-1 was pelletized without beingblended with tris(4-nonylphenyl)phosphite,tris(2,4-di-t-butylphenyl)phosphite or octadecyl3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, and evaluated forresistances to heat and hydrolysis. The results are given in the Table13.

Comparative Example M-2

Another polycarbonate was prepared in the same manner as that of ExampleM-2 except that a known catalyst for comparison, i.e., lithium hydroxidewhich is an alkali metal hydroxide was used instead of 2-methylimidazolein an amount of 10⁻³ mole % based on the 2,2-bis(4-hydroxyphenyl)propaneused and that no tris(4-nonylphenyl)phosphite, notetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite and nooctadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate was added.

Although the obtained polymer had an average molecular weight as high as26,500, the polymer was pale-yellow; the thermal decomposition thereofbegan at 375° C.; and the weight loss to reach 430° C. was 10%. Further,in the hydrolysis test at 90° C. and 100% RH, the retention of averagemolecular weight after 30 days was as low as 65.3% and the resultingtest sheet was translucent, had many small white spots (partiallyincluding voids) all over and was brittle remarkably.

These results are given in Table 13.

                                      TABLE 13                                    __________________________________________________________________________              Ex. M-1      Ex. M-2      Ex. M-3      Ex. M-4                      __________________________________________________________________________    Dihydroxy 2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-                                                                  2,2-bis(4-hydroxyphenyl)-    compound  propane      propane      propane      propane (50 mole                                                              %)/2,2-                                                                       bis(4-hydroxy-3-t-butyl-                                                      phenyl)propane (50 mole                                                       %)                           Bisaryl carbonate                                                                       diphenyl carbonate                                                                         diphenyl carbonate                                                                         diphenyl carbonate                                                                         diphenyl carbonate           Catalyst  potassium borohydride                                                                      2-methylimidazole                                                                          dimethylamine-borane                                                                       4-dimethylaminopyridine                                          complex                                   Phosphite or                                                                            tris(4-nonylphenyl)                                                                        tris(4-nonylphenyl)                                                                        tridecyl phosphite (33.3                                                                   tris(4-nonylphenyl)          phosphonite                                                                             phosphite (50 wt                                                                           phosphite (50 wt %)/                                                                       wt %)/bis(2,6-di-t-butyl-4-                                                                phosphite (50 wt %)/         compound  %)/tris(2,4-di-t-                                                                          tetrakis(2,4-di-t-butyl-                                                                   methylphenyl)penta-                                                                        tetrakis(2,4-di-t-butyl-               butylphenyl) phenyl)-4,4'-biphenylene-                                                                  erythritol diphosphite                                                                     phenyl)-4,4'-biphenylene-              phosphite (50 wt %)                                                                        diphosphonite (50 wt %)                                                                    (33.3 wt %)/tetrakis(2,4-di-                                                               diphosphonite (50 wt %)                                          t-butylphenyl)-4,4'-                                                          biphenylenediphosphonite                                                      (33.3 wt %)                                                      (rel. soln. viscosity at                                                      addn.: 1.18)                                           Hindered phenol                                                                         octadecyl 3-(3',5'-di-t-                                                                   octadecyl 3-(3',5'-di-t-                                                                   octadecyl 3-(3',5'-di-t-                                                                   octadecyl                                                                     3-(3',5'-di-t-               compound  butyl-4'-hydroxyphenyl)-                                                                   butyl-4'-hydroxyphenyl)-                                                                   butyl-4'-hydroxyphenyl)-                                                                   butyl-4'-hydroxyphenyl)-               propionate   propionate   propionate   propionate                   Hue of    nearly colorless                                                                           nearly colorless                                                                           nearly colorless                                                                           nearly colorless             polycondensate                                                                Av. mol. wt. of                                                                         24,300       27,000       23,300       25,000                       polycondensate                                                                Thermogravimetric                                                             analysis                                                                      T.sub.d   430° C.                                                                             432° C.                                                                             430° C.                                                                             430° C.               T.sub.5   470° C.                                                                             470° C.                                                                             469° C.                                                                             469° C.               T.sub.10  485° C.                                                                             486° C.                                                                             483° C.                                                                             482° C.               After hydrolysis for                                                          30 days at 90° C.                                                      and 100% RH                                                                   appearance                                                                              colorless and transparent                                                                  colorless and transparent                                                                  colorless and transparent                                                                  colorless and                                                                 transparent                  retention of mol. wt.                                                                   89.0%        88.2%        89.1%        87.0%                        __________________________________________________________________________                    Ex. M-5         Comp. Ex. M-1  Comp. Ex.                      __________________________________________________________________________                                                   M-2                            Dihydroxy compound                                                                            2,2-bis(4-hydroxyphenyl)-                                                                     2,2-bis(4-hydroxyphenyl)-                                                                    2,2-bis(4-hydroxyphenyl)-                      propane         propane        propane                        Bisaryl carbonate                                                                             bis(2,4,6-trichlorophenyl)                                                                    diphenyl carbonate                                                                           diphenyl carbonate                             carbonate                                                     Catalyst        dimethylaminopyridine                                                                         potassium borohydride                                                                        lithium hydroxide              Phosphite or phosphonite                                                                      tris(4-nonylphenyl)phosphite                                                                  --             --                             compound        (50 wt %)/tris(2,4-di-t-butyl-                                                phenyl)phosphite (50 wt %)                                                    (rel. soln. viscosity at                                                      addn.: 1.19)                                                  Hindered phenol compound                                                                      octadecyl 3-(3',5'-di-t-                                                                      --             --                                             butyl-4'-hydroxyphenyl)-                                                      propionate                                                    Hue of polycondensate                                                                         nearly colorless                                                                              nearly colorless                                                                             pale-yellow                    Av. mol. wt. of 26,800          24,300         26,500                         polycondensate                                                                Thermogravimetric analysis                                                    T.sub.d         432° C.  380° C. 375° C.                 T.sub.5         470° C.  415° C. 414° C.                 T.sub.10        485° C.  435° C. 430° C.                 After hydrolysis for 30                                                       days at 90° C. and 100% RH                                             appearance      colorless and transparent                                                                     translucent    translucent                    retention of mol. wt.                                                                         86.9%           68.0%          65.3%                          __________________________________________________________________________

What we claimed is:
 1. A melt polycondensation process for producing a(co)polycarbonate or a (co)polyestercarbonate by reacting an aromaticdihydroxyl compound with one or more members selected from the groupconsisting of a diester of carbonic acid and a diester of dicarboxylicacid in the presence of a transesterification catalyst, wherein at leastpart of the reacting is conducted in the presence of an organicphosphorus compound selected from the group consisting of compoundsrepresented by the following general formulas ( 1) to (6), or, in thepresence of an organic phosphorus compound selected from the groupconsisting of compounds represented by the following general formulas(1) to (6) and a hindered phenol compound: ##STR44## wherein R^(a),R^(b) and R^(c) each represents a straight-chain or branched alkyl grouphaving 1 to 12 carbon atoms, or a phenyl group which is unsubstituted orsubstituted; ##STR45## wherein R^(d), R^(e), R^(f), R^(g), R^(h), R^(i),R^(j) and R^(k) each represents a hydrogen atom or a straight-chain orbranched alkyl group having 1 to 12 carbon atoms, R^(q) and R^(r) eachrepresents a straight-chain or branched alkyl group having 1 to 12carbon atoms and R^(s) and R^(t) each represents a straight-chain orbranched alkyl group having 1 to 12 carbon atoms; ##STR46## whereinR^(u) and R^(v) each represents a straight-chain or branched alkyl grouphaving 1 to 20 carbon atoms and R^(w) represents a phenyl or aralkylgroup which is substituted or unsubstituted, wherein the organicphosphorus compound and the hindered phenol compound are added after therelative viscosity of the reaction mixture reaches in the range of from1.01 to 1.15 (polymer content: 0.5 g/dl in methylene chloride, at 20°C.).
 2. A melt polycondensation process for producing a(co)polycarbonate or a (co)polyestercarbonate by reacting an aromaticdihydroxyl compound with one or more members selected from the groupconsisting of a diester of carbonic acid and a diester of dicarboxylicacid in the presence of a transesterification catalyst, wherein at leastpart of the reacting is conducted in the presence or an organicphosphorus compound selected from the group consisting of compoundsrepresented by the following general formulas (1) to (6), or, in thepresence of an organic phosphorus compound selected from the groupconsisting of compounds represented by the following general formulas(1) to (6) and a hindered phenol compound: ##STR47## wherein R^(a),R^(b) and R^(c) each represents a straight-chain or branched alkyl grouphaving 1 to 12 carbon atoms, or a phenyl group which is unsubstituted orsubstituted; ##STR48## wherein R^(d), R^(e), R^(f), R^(g), R^(h), R^(i),R^(j) and R^(k) each represents a hydrogen atom or a straight-chain orbranched alkyl group having 1 to 12 carbon atoms, R^(q) and R^(r) eachrepresents a straight-chain or branched alkyl group having 1 to 12carbon atoms and R^(s) and R^(t) each represents a straight-chain orbranched alkyl group having 1 to 12 carbon atoms; ##STR49## whereinR^(u) and R^(v) each represents a straight-chain or branched alkyl grouphaving 1 to 20 carbon atoms and R^(w) represents a phenyl or aralkylgroup which is substituted or unsubstituted, wherein the organicphosphorus compound is added before the relative viscosity of thereaction mixture reaches in the range of from 1.01 to 1.15 (polymercontent: 0.5 g/dl in methylene chloride, at 20° C.), and the hinderedphenol compound is added after the relative viscosity of the reactionmixture reaches in the range of from 1.01 to 1.15 (polymer content: 0.5g/dl in methylene chloride, at 20° C.).
 3. A melt polycondensationprocess for producing a (co)polycarbonate or a (co)polyestercarbonate byreacting an aromatic dihydroxyl compound with one or more membersselected from the group consisting of a diester of carbonic acid and adiester of dicarboxylic acid in the presence of a transesterificationcatalyst, wherein at least part of the reacting is conducted in thepresence of an organic phosphorus compound selected from the groupconsisting of compounds represented by the following general formulas(1) to (6), or, in the presence of an organic phosphorus compoundselected from the group consisting of compounds represented by thefollowing general formulas (1) to (6) and a hindered phenol compound:##STR50## wherein R^(a), R^(b) and R^(c) each represents astraight-chain or branched alkyl group having 1 to 12 carbon atoms, or aphenyl group which is unsubstituted or substituted; ##STR51## whereinR^(d), R^(e), R^(f), R^(g), R^(h), R^(i), R^(j) and R^(k) eachrepresents a hydrogen atom or a straight-chain or branched alkyl grouphaving 1 to 12 carbon atoms, R^(q) and R^(r) each represents astraight-chain or branched alkyl group having 1 to 12 carbon atoms andR^(s) and R^(t) each represents a straight-chain or branched alkyl grouphaving 1 to 12 carbon atoms; ##STR52## wherein R^(u) and R^(v) eachrepresents a straight-chain or branched alkyl group having 1 to 20carbon atoms and R^(w) represents a phenyl or aralkyl group which may besubstituted or unsubstituted, wherein the hindered phenol compound isadded before the relative viscosity of the reaction mixture reaches inthe range of from 1.01 to 1.15 (polymer content: 0.5 g/dl in methylenechloride, at 20° C.), and the organic phosphorus compound is added afterthe relative viscosity of the reaction mixture reaches in the range offrom 1.01 to 1.15 (polymer content: 0.5 g/dl in methylene chloride, at20° C.).
 4. The process of claim 1, wherein the transesterificationcatalyst is a basic compound containing a nitrogen atom in its moleculeor a basic compound containing a nitrogen atom in its molecule and analkaline metal compound and/or an alkaline earth metal compound.
 5. Theprocess of claim 2, wherein the transesterification catalyst is a basiccompound containing a nitrogen atom in its molecule or a basic compoundcontaining a nitrogen atom in its molecule and an alkaline metalcompound and/or an alkaline earth metal compound.
 6. The process ofclaim 3, wherein the transesterification catalyst is a basic compoundcontaining a nitrogen atom in its molecule or a basic compoundcontaining a nitrogen atom in its molecule and an alkaline metalcompound and/or an alkaline earth metal compound.
 7. The process ofclaim 1, wherein at least part of the reacting is conducted in thepresence of said organic phosphorus compound and said hindered phenolcompound.
 8. The process of claim 2, wherein at least part of thereacting is conducted in the presence of said organic phosphoruscompound and said hindered phenol compound.
 9. The process of claim 3,wherein at least part of the reacting is conducted in the presence ofsaid organic phosphorus compound and said hindered phenol compound. 10.The process of claim 4, wherein the basic compound is selected from thegroup consisting of primary amines, secondary amines, tertiary amines,ammonia, ammonium hydroxides, ammonium borohydrides, ammoniumtetraarylborates, pyridines, imidazoles, diazo compounds, picolines,pyrimidines, quinolines, pyrazoles, aniline, pyrrolidines, morpholines,piperidines and piperadines.
 11. The process of claim 5, wherein thebasic compound is selected from the group consisting of primary amines,secondary amines, tertiary amines, ammonia, ammonium hydroxides,ammonium borohydrides, ammonium tetraarylborates, pyridines, imidazoles,diazo compounds, picolines, pyrimidines, quinolines, pyrazoles, aniline,pyrrolidines, morpholines, piperidines and piperadines.
 12. The processof claim 6, wherein the basic compound is selected from the groupconsisting of primary amines, secondary amines, tertiary amines,ammonia, ammonium hydroxides, ammonium borohydrides, ammoniumtetraarylborates, pyridines, imidazoles, diazo compounds, picolines,pyrimidines, quinolines, pyrazoles, aniline, pyrrolidines, morpholines,piperidines and piperadines.